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Printable Cell Holder Generator

Provides a Python script to generate custom .step files for 3D-printable battery cell holders. You can easily define the dimensions, cell size, spacing, and other features.

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Usage

To generate a cell holder, run the script from your terminal using the following command structure.

python3 layout_step.py <x_dim> <y_dim> <spacing> <cell_size> <cover_thickness> <rounded_corners> <bms_holes> <ledge_width> [fillet_bms]

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Setup venv

Before running the script, it is recommended to create a Python virtual environment and install the required dependencies.

1. Create a venv:

python3 -m venv venv

2. Activate the venv:

Linux/macOS:

source venv/bin/activate

Windows (PowerShell):

.\venv\Scripts\Activate.ps1

3. Install the dependencies:

pip install -r requirements.txt

Note: If your Python version is above 3.12 and the installed cadquery version is below 2.5.2, the standard requirements.txt installation may fail. In that case, install Python 3.11, create the venv through that version.

Parameters

The script accepts the following arguments in order:

Parameter	Description	Data Type
x_dim, y_dim	Total allowed width & length in mm.	float
spacing	The minimum wall thickness between cell holes. (e.g., 0.43 for a 0.4mm nozzle).	float
cell_size	The diameter of your battery cell, including any desired tolerance (e.g., 21.4-21.7 for a 21700 cell).	float
cover_thickness	The thickness of the ledge_width. (0.2-0.4 is normal)	float
rounded_corners	Rounded external corners on the holder.	true / false
bms_holes	Adds mounting holes for balancing.	true / false
ledge_width	Cover ledge in mm, 3.75 to mimic fishpaper.	float
fillet_bms	(Optional, causes segmentation fault <18.5 cells) Adds a fillet to the balancing holes.	true / false

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Example

Here is an example command for generating a holder for 21700 cells, optimized for printing with a 0.4mm nozzle.

python3 layout_step.py 100 100 0.43 21.5 0.4 true true 3.75 true