diff --git a/README.md b/README.md
index 4111b4d..35a3c07 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,22 @@ As above, plus also `pip install -Ur requirements/requirements-dev.txt` to get l
 
 ## Tools
 
+In all cases, online help can be retrieved by providing the `-h` or ``--help`` flags to the below programs.
+
+### concatenate
+
+**concatenate** combines a GP2040-CE firmware .bin file (such as from a fresh build) and a GP2040-CE board's storage
+section .bin, and produces a properly-offset .bin file suitable for flashing to a board. This may be useful to ensure
+the board is flashed with a particular configuration, for instances such as producing a binary to flash many boards with
+a particular configuration (specific customizations, etc.), or keeping documented backups of what you're testing with
+during development.
+
+Sample usage:
+
+```
+% concatenate build/GP2040-CE_foo_bar.bin storage-dump.bin new-firmware-with-config.bin
+```
+
 ### visualize-storage
 
 **visualize-storage** reads a dump of a GP2040-CE board's flash storage section, where the configuration lives, and
@@ -121,6 +137,7 @@ context. The storage section of a GP2040-CE board is a reserved 8 KB starting at
 ```
 
 And to dump your whole board:
+
 ```
 % picotool save -a whole-board.bin
 ```
diff --git a/gp2040ce_bintools/builder.py b/gp2040ce_bintools/builder.py
new file mode 100644
index 0000000..313f88a
--- /dev/null
+++ b/gp2040ce_bintools/builder.py
@@ -0,0 +1,69 @@
+"""Build binary files for a GP2040-CE board."""
+import argparse
+import logging
+
+from gp2040ce_bintools import core_parser
+from gp2040ce_bintools.storage import STORAGE_LOCATION
+
+logger = logging.getLogger(__name__)
+
+
+#################
+# LIBRARY ITEMS #
+#################
+
+
+class FirmwareLengthError(ValueError):
+    """Exception raised when the firmware is too large to fit the known storage location."""
+
+
+def concatenate_firmware_and_storage_files(firmware_filename: str, storage_filename: str, combined_filename: str):
+    """Open the provided binary files and combine them into one combined GP2040-CE with config file.
+
+    Args:
+        firmware_filename: filename of the firmware binary to read
+        storage_filename: filename of the storage section to read
+        combined_filename: filename of where to write the combine binary
+    """
+    with open(firmware_filename, 'rb') as firmware, open(storage_filename, 'rb') as storage:
+        new_binary = pad_firmware_up_to_storage(firmware.read()) + bytearray(storage.read())
+    with open(combined_filename, 'wb') as combined:
+        combined.write(new_binary)
+
+
+def pad_firmware_up_to_storage(firmware: bytes) -> bytearray:
+    """Provide a copy of the firmware padded with zero bytes up to the provided position.
+
+    Args:
+        firmware: the read-in binary file to process
+    Returns:
+        the resulting padded binary as a bytearray
+    Raises:
+        FirmwareLengthError: if the firmware is larger than the storage location
+    """
+    bytes_to_pad = STORAGE_LOCATION - len(firmware)
+    logger.debug("firmware is length %s, padding %s bytes", len(firmware), bytes_to_pad)
+    if bytes_to_pad < 0:
+        raise FirmwareLengthError(f"provided firmware binary is larger than the start of "
+                                  f"storage at {STORAGE_LOCATION}!")
+
+    return bytes(bytearray(firmware) + bytearray(b'\x00' * bytes_to_pad))
+
+
+############
+# COMMANDS #
+############
+
+def concatenate():
+    """Combine a built firmware .bin and a storage .bin."""
+    parser = argparse.ArgumentParser(
+        description="Combine a compiled GP2040-CE firmware-only .bin and an existing storage area .bin into one file "
+                    "suitable for flashing onto a board.",
+        parents=[core_parser],
+    )
+    parser.add_argument('firmware_filename', help=".bin file of a GP2040-CE firmware, probably from a build")
+    parser.add_argument('storage_filename', help=".bin file of a GP2040-CE board's storage section")
+    parser.add_argument('new_binary_filename', help="output .bin file of the resulting firmware + storage")
+
+    args, _ = parser.parse_known_args()
+    concatenate_firmware_and_storage_files(args.firmware_filename, args.storage_filename, args.new_binary_filename)
diff --git a/pyproject.toml b/pyproject.toml
index f219e86..eb40e1d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,6 +19,7 @@ dev = ["bandit", "decorator", "flake8", "flake8-blind-except", "flake8-builtins"
        "flake8-pyproject", "mypy", "pip-tools", "pytest", "pytest-cov", "setuptools-scm", "tox"]
 
 [project.scripts]
+concatenate = "gp2040ce_bintools.builder:concatenate"
 visualize-storage = "gp2040ce_bintools.storage:visualize"
 
 [tool.flake8]
diff --git a/tests/conftest.py b/tests/conftest.py
index 23fdcae..4062aa9 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -6,6 +6,16 @@ import pytest
 HERE = os.path.dirname(os.path.abspath(__file__))
 
 
+@pytest.fixture
+def firmware_binary():
+    """Read in a test GP2040-CE firmware binary file."""
+    filename = os.path.join(HERE, 'test-files', 'test-firmware.bin')
+    with open(filename, 'rb') as file:
+        content = file.read()
+
+    yield content
+
+
 @pytest.fixture
 def storage_dump():
     """Read in a test storage dump file (101FE000-10200000) of a GP2040-CE board."""
diff --git a/tests/test-files/test-firmware.bin b/tests/test-files/test-firmware.bin
new file mode 100644
index 0000000..8827ffb
Binary files /dev/null and b/tests/test-files/test-firmware.bin differ
diff --git a/tests/test_builder.py b/tests/test_builder.py
new file mode 100644
index 0000000..a5829a9
--- /dev/null
+++ b/tests/test_builder.py
@@ -0,0 +1,16 @@
+"""Tests for the image builder module."""
+import pytest
+
+from gp2040ce_bintools.builder import FirmwareLengthError, pad_firmware_up_to_storage
+
+
+def test_padding_firmware(firmware_binary):
+    """Test that firmware is padded to the expected size."""
+    padded = pad_firmware_up_to_storage(firmware_binary)
+    assert len(padded) == 2088960
+
+
+def test_padding_firmware_too_big(firmware_binary):
+    """Test that firmware is padded to the expected size."""
+    with pytest.raises(FirmwareLengthError):
+        _ = pad_firmware_up_to_storage(firmware_binary + firmware_binary + firmware_binary)
diff --git a/tests/test_commands.py b/tests/test_commands.py
index fa2a681..831c613 100644
--- a/tests/test_commands.py
+++ b/tests/test_commands.py
@@ -1,5 +1,6 @@
 """Test our tools themselves to make sure they adhere to certain flags."""
 import json
+import os
 from subprocess import run
 
 from gp2040ce_bintools import __version__
@@ -18,6 +19,17 @@ def test_help_flag():
     assert 'Read the configuration section from a dump of a GP2040-CE board' in result.stdout
 
 
+def test_concatenate_invocation(tmpdir):
+    """Test that a normal invocation against a dump works."""
+    out_filename = os.path.join(tmpdir, 'out.bin')
+    _ = run(['concatenate', 'tests/test-files/test-firmware.bin', 'tests/test-files/test-storage-area.bin',
+             out_filename])
+    with open(out_filename, 'rb') as out_file, open('tests/test-files/test-storage-area.bin', 'rb') as storage_file:
+        out = out_file.read()
+        storage = storage_file.read()
+    assert out[2088960:2097152] == storage
+
+
 def test_storage_dump_invocation():
     """Test that a normal invocation against a dump works."""
     result = run(['visualize-storage', '-P', 'tests/test-files/proto-files', 'tests/test-files/test-storage-area.bin'],