The existing acrylic paint holders didn't work for me, so I designed one from scratch in Fusion360, using the others as inspiration. I've included several layouts depending on your needs and print bed. A 7x7 should fit on a 300x300 bed (CR-10 series), and a 5x5 should fit on a 220x220 bed (Ender3).
Important: This is optimized for a LINE WIDTH of 0.4 and NO infill. Please preview the code after slicing, to make sure your lines look like the screenshots, with no broken or partial lines. 3 lines per outer wall and 6 lines per inner/double wall.
Please get your retraction settings dialed in before printing, or you'll have a lot of cleanup to do. I prefer the stringing test found here: https://www.thingiverse.com/thing:2450004
If you have a little stringing anyway, run over it with a heat gun and the strings should shrivel up and be easy to scrape off.