Minimal colorization jig for PET strips

This is a very minimal jig for sliding a cut PET bottle strip through to colorize it before turning it into filament with a pultrusion machine. Just hold a wide-tip permanent marker against the strip through the window and pull. The opening is designed to admit strips that curl from cutting the bottom or top segment of a bottle.

The jig prints without supports in a 45° orientation as in the STL file. Provided STL allows strips up to 10mm wide and 0.7 mm thick. If you need a wider opening or a more constraining path for narrower strips, the customizer/OpenSCAD source file can be used to produce variants.

Usage demo video: https://youtube.com/shorts/rYKTfnku9vg