Summary

The insert for this game is practically non-existent, so I went looking for a way to organize the card stacks. I came across this design on BoardGameGeek, but the base is one solid piece that won't fit on my print bed. I decided to draw up a new sketch, modified the trays based on some of the feedback in the thread, made adjustments to allow for fingers, and added fillets and chamfers.

There are two versions of the trays, one with feet, one without. The feet keep the trays from sliding around when stacking, which is helpful if you intend to use them outside of the box. Otherwise, the fit is tight enough in the box that the feet aren't necessary.

Print notes:

• I printed the two main halves with infill only for the bottom. You can do this by adding the stl in your slicer and adding a modifier box over the bottom, about 4 mm tall. Then select the modifier and change the settings to 0 top and bottom layers and grid infill. Once these were printed, I glued them together with superglue and clamped them for about 30 minutes.
• If you want to print the trays with feet, you'll need to print them on a bed of support, which will need to be removed with a sharp scraper. Work slowly around the corners or you might slip and jab a finger (like I did ;P ). The bed of support leaves a rough bottom surface. See the last photo.

Misc.:
The left side of the main tray in the photos is a print of an earlier design, before I made adjustments for fingers. The right side of the main tray was printed with those adjustments, so I didn't reprint the left half.