Cherry MX Keycap that accept printed paper inserts. Mark macro keys, highlight often used functions or simply added a bit of decoration.

Key inserts are printed on paper, cut and slid into place. Adding a layer of clear tape makes the insert more durable. A dab of glue can be used to permanent affix the insert.

Inserts are roughly 13.7 x 11mm (0.54 x 0.44 inches). Layer height and quality seem to affect this so some trimming will likely be needed.

I found printing the keycap with the top parallel to the print bed works best. I do this in PrusaSlicer with the Place on face tool and selecting the top surface. Next rotate the keycap 180 degrees about the X or Y axis. This will require supports, but the new organic supports in PrisaSlicer 2.6.0 alpha 3 are a great.