Made for US banknotes, but configurable for any currency size. I made it with six slots (for 1, 5, 10, 20, 50, and 100 bills) with varying widths based on preference.

I printed mine with 2mm thick outer shell (shellWidth parameter), which is a little brittle but works for me. If I were to print again, I'd bump it up to 3mm (which is what these v2 files are saved as).

Note the hexagon pattern is resource heavy and takes a while to recalculate. If there's a better way to do these patterns, this rank amateur is open to suggestions.