Summary

This provides a customizable OpenSCAD model for alphabet cookie cutters. For your convenience, I have uploaded STL files for the English alphabet (A-Z) with four letters per file. There's no reason that other alphabets shouldn't work equally as well.

OpenSCAD is slooooow at rendering the parts unless you use a recent "Nightly Build" of OpenSCAD that uses the "Manifold" rendering backend. The source code has instructions on how to do this. I have enabled customization on Thingiverse, but this might not be practical if it takes too long to render.

The portion of the code for generating tapered extrusions was developed by Stewart Russell (CC-BY-SA)

It took me about a half-kilogram of PETG filament to print all 26 letters.