diff --git a/.github/scripts/nightly.sh b/.github/scripts/nightly.sh
new file mode 100644
index 0000000000..ec5ba9af7b
--- /dev/null
+++ b/.github/scripts/nightly.sh
@@ -0,0 +1,106 @@
+#!/bin/bash
+
+##########################################################
+# Build and test the GTSAM Python wrapper.
+##########################################################
+
+set -x -e
+
+# install TBB with _debug.so files
+function install_tbb()
+{
+  echo install_tbb
+  if [ "$(uname)" == "Linux" ]; then
+    sudo apt-get -y install libtbb-dev
+
+  elif [ "$(uname)" == "Darwin" ]; then
+    brew install tbb
+  fi
+}
+
+if [ -z ${PYTHON_VERSION+x} ]; then
+    echo "Please provide the Python version to build against!"
+    exit 127
+fi
+
+export PYTHON="python${PYTHON_VERSION}"
+
+function install_dependencies()
+{
+  if [[ $(uname) == "Darwin" ]]; then
+    brew install wget
+  else
+    # Install a system package required by our library
+    sudo apt-get install -y wget libicu-dev python3-pip python3-setuptools
+  fi
+
+  export PATH=$PATH:$($PYTHON -c "import site; print(site.USER_BASE)")/bin
+
+  if [ "${GTSAM_WITH_TBB:-OFF}" == "ON" ]; then
+    install_tbb
+  fi
+}
+
+# Chirality exception is thrown by the camera projection when the solver
+# randomly places the camera such that the landmarks are behind it.
+# This breaks the dependent python custom factor with numeric derivatives.
+
+# Build needs to be static to be included in the wheel at the end.
+
+function build()
+{
+  export CMAKE_GENERATOR=Ninja
+  BUILD_PYBIND="ON"
+  cmake $GITHUB_WORKSPACE \
+      -B build \
+      -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE} \
+      -DGTSAM_BUILD_TESTS=OFF \
+      -DGTSAM_FORCE_SHARED_LIB=OFF \
+      -DGTSAM_BUILD_UNSTABLE=${GTSAM_BUILD_UNSTABLE:-ON} \
+      -DGTSAM_THROW_CHEIRALITY_EXCEPTION=OFF \
+      -DGTSAM_USE_QUATERNIONS=OFF \
+      -DGTSAM_WITH_TBB=${GTSAM_WITH_TBB:-OFF} \
+      -DGTSAM_BUILD_EXAMPLES_ALWAYS=OFF \
+      -DGTSAM_BUILD_WITH_MARCH_NATIVE=OFF \
+      -DGTSAM_BUILD_PYTHON=${BUILD_PYBIND} \
+      -DBUILD_SHARED_LIBS=OFF \
+      -DBUILD_STATIC_METIS=ON \
+      -DGTSAM_UNSTABLE_BUILD_PYTHON=${GTSAM_BUILD_UNSTABLE:-ON} \
+      -DGTSAM_PYTHON_VERSION=$PYTHON_VERSION \
+      -DPYTHON_EXECUTABLE:FILEPATH=$(which $PYTHON) \
+      -DGTSAM_ALLOW_DEPRECATED_SINCE_V43=OFF \
+      -DCMAKE_INSTALL_PREFIX=$GITHUB_WORKSPACE/gtsam_install
+
+
+  # Set to 2 cores so that Actions does not error out during resource provisioning.
+  cmake --build build -j2
+
+  cmake --build build --target python-install
+}
+
+function test()
+{
+  cd $GITHUB_WORKSPACE/python/gtsam/tests
+  $PYTHON -m unittest discover -v
+  cd $GITHUB_WORKSPACE
+
+  cd $GITHUB_WORKSPACE/python/gtsam_unstable/tests
+  $PYTHON -m unittest discover -v
+  cd $GITHUB_WORKSPACE
+
+  # cmake --build build --target python-test
+  # cmake --build build --target python-test-unstable
+}
+
+# select between build or test
+case $1 in
+  -d)
+    install_dependencies
+    ;;
+  -b)
+    build
+    ;;
+  -t)
+    test
+    ;;
+esac
diff --git a/.github/workflows/arm-nightly.yml b/.github/workflows/arm-nightly.yml
new file mode 100644
index 0000000000..348db80447
--- /dev/null
+++ b/.github/workflows/arm-nightly.yml
@@ -0,0 +1,111 @@
+# Nightly build for Raspberry Pi
+# Uploads to test.pypi.org.
+
+name: ARM Nightly
+
+on: [workflow_dispatch]
+
+env:
+  IMG: raspios_lite_arm64:latest
+  BIND: true
+  CPU: cortex-a76
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-24.04
+    # strategy:
+    #   fail-fast: false
+    #   matrix:
+    #     python_version: ['3.9', '3.10', '3.11', '3.12']
+
+
+    env:
+      # quote the number because yaml thinks 3.10 and 3.1 are the same, like it's a number, man.
+      # https://yaml.org/spec/1.2.2/ the yaml spec is 50 pages
+      PYTHON_VERSION: '3.11'
+      # PYTHON_VERSION: ${{matrix.python_version}}
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: env
+        run: |
+            echo "=== SET VARS ==="            
+            echo "CC=gcc" >> $GITHUB_ENV
+            echo "CXX=g++" >> $GITHUB_ENV
+            echo "NIGHTLY=1" >> $GITHUB_ENV
+
+      - name: Run on ARM
+        uses: pguyot/arm-runner-action@v2
+        with:
+          base_image: $IMG
+          bind_mount_repository: $BIND
+          copy_repository_path: /home/runner/work/gtsam/gtsam
+          cpu: $CPU
+          debug: true
+          image_additional_mb: 20000
+          commands: |
+            echo "=== CPU INFO ==="
+            cat /proc/cpuinfo
+            echo "=== UPDATE ==="
+            sudo apt-get -y update
+            echo "=== INSTALL 1 ==="
+            sudo apt-get -y install python3 cmake build-essential pkg-config python3-numpy
+            echo "=== INSTALL 2 ==="
+            sudo apt-get -y install libboost-all-dev ninja-build 
+            echo "=== INSTALL 3 ==="
+            sudo apt-get -y install g++ patchelf
+            echo "=== DEPEND ==="
+            bash .github/scripts/nightly.sh -d
+            echo "=== REQ ==="
+            python3 -m pip install --break-system-packages -r python/dev_requirements.txt
+            echo "=== PWD ==="
+            pwd
+            echo "=== ls ==="
+            ls -R
+            echo "=== BUILD ==="
+            bash .github/scripts/nightly.sh -b
+            echo "=== TEST ==="
+            bash .github/scripts/nightly.sh -t
+            echo "=== INSTALL AUDITWHEEL ==="
+            python3 -m pip install --break-system-packages --upgrade pip auditwheel
+            echo "=== BUILD WHEEL ==="
+            python3 -m pip wheel build/python -w build/python/dist
+            echo "=== CHECK LDD VERSION ==="
+            ldd --version
+            echo "=== AUDITWHEEL ==="
+            python3 -m auditwheel repair --plat manylinux_2_35_aarch64 -w build/python/repaired/ build/python/dist/truher_gtsam_nightly*
+
+
+      - name: Upload Artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          # TODO: define the name as ENV, use it in CMakeLists.txt 
+          name: artifact311
+          # name: artifact${{matrix.python_version}}
+          path: build/python/repaired/truher_gtsam_nightly*
+      
+
+  upload_all:
+    # Waits for all the builds to finish
+    # Downloads all their wheels
+    # Uploads them all at once.
+    name: Upload All
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+    steps:
+      - name: Download Artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: dist/
+          merge-multiple: true
+
+      - name: Publish
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          packages-dir: dist/
+          repository-url: https://test.pypi.org/legacy/
\ No newline at end of file
diff --git a/.github/workflows/build-linux.yml b/.github/workflows/build-linux.yml
index da398ad235..6d1c4ce0c5 100644
--- a/.github/workflows/build-linux.yml
+++ b/.github/workflows/build-linux.yml
@@ -1,6 +1,6 @@
 name: Linux CI
 
-on: [pull_request]
+on: [pull_request, workflow_dispatch]
 
 # Every time you make a push to your PR, it cancel immediately the previous checks, 
 # and start a new one. The other runner will be available more quickly to your PR. 
diff --git a/.github/workflows/build-macos.yml b/.github/workflows/build-macos.yml
index e519164ec3..233cb9b4a7 100644
--- a/.github/workflows/build-macos.yml
+++ b/.github/workflows/build-macos.yml
@@ -1,6 +1,6 @@
 name: macOS CI
 
-on: [pull_request]
+on: [pull_request, workflow_dispatch]
 
 # Every time you make a push to your PR, it cancel immediately the previous checks, 
 # and start a new one. The other runner will be available more quickly to your PR. 
diff --git a/.github/workflows/build-python.yml b/.github/workflows/build-python.yml
index 24a7f6c90e..f9ced83256 100644
--- a/.github/workflows/build-python.yml
+++ b/.github/workflows/build-python.yml
@@ -1,6 +1,6 @@
 name: Python CI
 
-on: [pull_request]
+on: [pull_request, workflow_dispatch]
 
 # Every time you make a push to your PR, it cancel immediately the previous checks,
 # and start a new one. The other runner will be available more quickly to your PR.
diff --git a/.github/workflows/build-special.yml b/.github/workflows/build-special.yml
index 3a7dd974dc..abd0af7fc4 100644
--- a/.github/workflows/build-special.yml
+++ b/.github/workflows/build-special.yml
@@ -1,6 +1,6 @@
 name: Special Cases CI
 
-on: [pull_request]
+on: [pull_request, workflow_dispatch]
 
 # Every time you make a push to your PR, it cancel immediately the previous checks, 
 # and start a new one. The other runner will be available more quickly to your PR. 
diff --git a/.github/workflows/build-windows.yml b/.github/workflows/build-windows.yml
index 20b4a846f9..89cbe61edd 100644
--- a/.github/workflows/build-windows.yml
+++ b/.github/workflows/build-windows.yml
@@ -1,6 +1,6 @@
 name: Windows CI
 
-on: [pull_request]
+on: [pull_request, workflow_dispatch]
 
 # Every time you make a push to your PR, it cancel immediately the previous checks, 
 # and start a new one. The other runner will be available more quickly to your PR. 
diff --git a/.github/workflows/linux-nightly.yml b/.github/workflows/linux-nightly.yml
new file mode 100644
index 0000000000..24bb78dfd4
--- /dev/null
+++ b/.github/workflows/linux-nightly.yml
@@ -0,0 +1,104 @@
+# Nightly build for Linux.
+# Uploads to test.pypi.org.
+
+name: Linux Nightly
+
+on: [workflow_dispatch]
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python_version: ['3.9', '3.10', '3.11', '3.12']
+
+
+    env:
+      # PYTHON_VERSION: '3.10'
+      PYTHON_VERSION: ${{matrix.python_version}}
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          #python-version: '3.10'
+          python-version: ${{matrix.python_version}}
+
+      - name: Install (Linux)
+        run: |
+          sudo apt-get -y update
+          sudo apt-get -y install cmake build-essential pkg-config python3-numpy libboost-all-dev ninja-build
+
+          sudo apt-get install -y g++ g++-multilib
+          echo "CC=gcc" >> $GITHUB_ENV
+          echo "CXX=g++" >> $GITHUB_ENV
+
+      - name: Set Swap Space (Linux)
+        uses: pierotofy/set-swap-space@master
+        with:
+          swap-size-gb: 6
+
+      - name: Install System Dependencies
+        run: bash .github/scripts/nightly.sh -d
+
+      - name: Install Python Dependencies
+        shell: bash
+        run: python3 -m pip install -r python/dev_requirements.txt
+
+      - name: Set Nightly Flag
+        run: echo "NIGHTLY=1" >> $GITHUB_ENV
+
+      - name: Build
+        # Builds the cmake "python-install" target which is a local install.
+        shell: bash
+        run: bash .github/scripts/nightly.sh -b
+
+      - name: Test
+        # Uses the local install for python3 -m unittest.
+        shell: bash
+        run: bash .github/scripts/python.sh -t
+
+      - name: Install Build Tools
+        run: python3 -m pip install --upgrade pip auditwheel
+
+      - name: Build for Publishing
+        run: python3 -m pip wheel build/python -w build/python/dist
+
+      - name: Repair Wheels
+        # TODO: use the actual glibc version here
+        run: python3 -m auditwheel repair --plat manylinux_2_35_x86_64 -w build/python/repaired/ build/python/dist/truher_gtsam_nightly*
+
+      - name: Upload Artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          # TODO: define the name as ENV, use it in CMakeLists.txt 
+          name: artifact${{matrix.python_version}}
+          path: build/python/repaired/truher_gtsam_nightly*
+      
+
+  upload_all:
+    # Waits for all the builds to finish
+    # Downloads all their wheels
+    # Uploads them all at once.
+    name: Upload All
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+    steps:
+      - name: Download Artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: dist/
+          merge-multiple: true
+
+      - name: Publish
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          packages-dir: dist/
+          repository-url: https://test.pypi.org/legacy/
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e3b462eec5..eea7029d81 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -25,10 +25,19 @@ set (GTSAM_VERSION_PATCH 0)
 set (GTSAM_PRERELEASE_VERSION "a0")
 math (EXPR GTSAM_VERSION_NUMERIC "10000 * ${GTSAM_VERSION_MAJOR} + 100 * ${GTSAM_VERSION_MINOR} + ${GTSAM_VERSION_PATCH}")
 
-if ("${GTSAM_PRERELEASE_VERSION}" STREQUAL "")
+# Use the current timestamp as the version string, if the "NIGHTLY" flag is set.
+if (DEFINED ENV{NIGHTLY})
+    string(TIMESTAMP NOW "%Y.%m.%d.%H.%M")
+    message(NOTICE "NIGHTLY BUILD ${NOW}")
+    set (GTSAM_VERSION_STRING "${NOW}")
+    # TODO: use the correct pypi nightly name
+    set (SETUP_NAME "truher-gtsam-nightly")
+elseif ("${GTSAM_PRERELEASE_VERSION}" STREQUAL "")
     set (GTSAM_VERSION_STRING "${GTSAM_VERSION_MAJOR}.${GTSAM_VERSION_MINOR}.${GTSAM_VERSION_PATCH}")
+    set (SETUP_NAME "gtsam")
 else()
     set (GTSAM_VERSION_STRING "${GTSAM_VERSION_MAJOR}.${GTSAM_VERSION_MINOR}${GTSAM_PRERELEASE_VERSION}")
+    set (SETUP_NAME "gtsam")
 endif()
 
 project(GTSAM
@@ -70,6 +79,7 @@ include(GtsamPrinting)
 
 ############### Decide on BOOST ######################################
 # Enable or disable serialization with GTSAM_ENABLE_BOOST_SERIALIZATION
+# (Serialization tests fail when this is off.)
 option(GTSAM_ENABLE_BOOST_SERIALIZATION "Enable Boost serialization" ON)
 if(GTSAM_ENABLE_BOOST_SERIALIZATION)
   add_definitions(-DGTSAM_ENABLE_BOOST_SERIALIZATION)
diff --git a/gtsam/3rdparty/cephes/CMakeLists.txt b/gtsam/3rdparty/cephes/CMakeLists.txt
index 190b73db9b..aafc45aa9c 100644
--- a/gtsam/3rdparty/cephes/CMakeLists.txt
+++ b/gtsam/3rdparty/cephes/CMakeLists.txt
@@ -89,7 +89,13 @@ set(CEPHES_SOURCES
     cephes/zetac.c)
 
 # Add library source files
-add_library(cephes-gtsam SHARED ${CEPHES_SOURCES})
+if (DEFINED ENV{NIGHTLY})
+  # Needs to be static for the nightly build to work.
+  add_definitions(-fPIC)
+  add_library(cephes-gtsam STATIC ${CEPHES_SOURCES})
+else()
+  add_library(cephes-gtsam SHARED ${CEPHES_SOURCES})
+endif()
 
 # Add include directory (aka headers)
 target_include_directories(
diff --git a/gtsam/nonlinear/nonlinear.i b/gtsam/nonlinear/nonlinear.i
index 09c234630e..5d15c11634 100644
--- a/gtsam/nonlinear/nonlinear.i
+++ b/gtsam/nonlinear/nonlinear.i
@@ -715,6 +715,9 @@ virtual class BatchFixedLagSmoother : gtsam::FixedLagSmoother {
   void print(string s = "BatchFixedLagSmoother:\n") const;
 
   gtsam::LevenbergMarquardtParams params() const;
+
+  gtsam::NonlinearFactorGraph getFactors() const;
+
   template <VALUE = {gtsam::Point2, gtsam::Rot2, gtsam::Pose2, gtsam::Point3,
                      gtsam::Rot3, gtsam::Pose3, gtsam::Cal3_S2, gtsam::Cal3DS2,
                      gtsam::Vector, gtsam::Matrix}>
diff --git a/python/CMakeLists.txt b/python/CMakeLists.txt
index f0fc3f796c..f5ddf95712 100644
--- a/python/CMakeLists.txt
+++ b/python/CMakeLists.txt
@@ -7,8 +7,16 @@ endif()
 
 # Generate setup.py.
 file(READ "${PROJECT_SOURCE_DIR}/README.md" README_CONTENTS)
-configure_file(${PROJECT_PYTHON_SOURCE_DIR}/setup.py.in
-               ${GTSAM_PYTHON_BUILD_DIRECTORY}/setup.py)
+
+if (DEFINED ENV{NIGHTLY})
+  # TODO: move all the builds to pyproject.toml
+  configure_file(${PROJECT_PYTHON_SOURCE_DIR}/pyproject.toml.in
+                 ${GTSAM_PYTHON_BUILD_DIRECTORY}/pyproject.toml)
+else()
+  configure_file(${PROJECT_PYTHON_SOURCE_DIR}/setup.py.in
+                 ${GTSAM_PYTHON_BUILD_DIRECTORY}/setup.py)
+endif()
+
 
 # Supply MANIFEST.in for older versions of Python
 file(COPY ${PROJECT_PYTHON_SOURCE_DIR}/MANIFEST.in
@@ -300,11 +308,20 @@ endif()
 # Note below we make sure to install with --user iff not in a virtualenv
 set(GTSAM_PYTHON_INSTALL_TARGET python-install)
 
-add_custom_target(${GTSAM_PYTHON_INSTALL_TARGET}
+if (DEFINED ENV{NIGHTLY})
+    # nightly requires breaking?  TODO: figure this out
+    add_custom_target(${GTSAM_PYTHON_INSTALL_TARGET}
+        COMMAND ${PYTHON_EXECUTABLE} -c "import sys, subprocess; cmd = [sys.executable, '-m', 'pip', 'install', '--break-system-packages']; has_venv = hasattr(sys, 'real_prefix') or (hasattr(sys, 'base_prefix') and sys.base_prefix != sys.prefix); cmd.append('--user' if not has_venv else ''); cmd.append('.'); subprocess.check_call([c for c in cmd if c])"
+        DEPENDS ${GTSAM_PYTHON_DEPENDENCIES} ${GTSAM_PYTHON_INSTALL_EXTRA}
+        WORKING_DIRECTORY ${GTSAM_PYTHON_BUILD_DIRECTORY}
+        VERBATIM)
+else()
+    add_custom_target(${GTSAM_PYTHON_INSTALL_TARGET}
         COMMAND ${PYTHON_EXECUTABLE} -c "import sys, subprocess; cmd = [sys.executable, '-m', 'pip', 'install']; has_venv = hasattr(sys, 'real_prefix') or (hasattr(sys, 'base_prefix') and sys.base_prefix != sys.prefix); cmd.append('--user' if not has_venv else ''); cmd.append('.'); subprocess.check_call([c for c in cmd if c])"
         DEPENDS ${GTSAM_PYTHON_DEPENDENCIES} ${GTSAM_PYTHON_INSTALL_EXTRA}
         WORKING_DIRECTORY ${GTSAM_PYTHON_BUILD_DIRECTORY}
         VERBATIM)
+endif()
 
 # Custom make command to run all GTSAM Python tests
 add_custom_target(
diff --git a/python/pyproject.toml.in b/python/pyproject.toml.in
new file mode 100644
index 0000000000..c9081bf3ed
--- /dev/null
+++ b/python/pyproject.toml.in
@@ -0,0 +1,55 @@
+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "${SETUP_NAME}"
+version = "${GTSAM_VERSION_STRING}"
+description = "Georgia Tech Smoothing And Mapping library"
+readme = "README.md"
+license = {text = "Simplified BSD license"}
+authors = [
+    { name = "Frank Dellaert et. al.", email = "frank.dellaert@gtsam.org" },
+]
+keywords = [
+    "localization",
+    "mapping",
+    "optimization",
+    "robotics",
+    "sam",
+    "slam",
+]
+classifiers = [
+    "Development Status :: 5 - Production/Stable",
+    "Intended Audience :: Developers",
+    "Intended Audience :: Education",
+    "Intended Audience :: Science/Research",
+    "License :: OSI Approved :: BSD License",
+    "Operating System :: MacOS",
+    "Operating System :: Microsoft :: Windows",
+    "Operating System :: POSIX",
+    "Programming Language :: Python :: 3",
+]
+dependencies = [
+    "numpy>=1.11.0,<2",
+]
+
+[project.urls]
+Homepage = "https://gtsam.org/"
+
+[tool.setuptools]
+ext-modules = [
+  {name = "gtsam", sources = []},
+  {name = "gtsam_unstable", sources = []}
+]
+
+[tool.setuptools.packages.find]
+where = ["."]
+exclude = ['build', 'build.*', 'CMakeFiles', 'CMakeFiles.*',
+           'gtsam.notebooks', '*.preamble', '*.specializations', 'dist']
+
+[tool.setuptools.package-data]
+"*" = ["./*.so",
+        "./*.dll",
+        "./*.pyd",
+        "*.pyi", "**/*.pyi"]
\ No newline at end of file
diff --git a/python/setup.py.in b/python/setup.py.in
index b9d7392c7e..8cd9c8fec2 100644
--- a/python/setup.py.in
+++ b/python/setup.py.in
@@ -21,7 +21,8 @@ package_data = {
 readme_contents = open("${GTSAM_SOURCE_DIR}/README.md").read()
 
 setup(
-    name='gtsam',
+    # This is set in the top-level CMakeLists.txt.
+    name='${SETUP_NAME}',
     description='Georgia Tech Smoothing And Mapping library',
     url='https://gtsam.org/',
     version='${GTSAM_VERSION_STRING}',  # https://www.python.org/dev/peps/pep-0440/