I was after a simple, yet elegant solution for holding two 20-sided dice, to mark wounds and experience for the board game Gloomhaven.
I intended to design something of my own, but found Jambro's "Large D20 Holder", which fit the bill nicely. I edited the "top" file in Sketchup Make, and resized it to suit the majority of d20s in my personal collection.
Now I can use d20s, and don't have to worry too much about an errant bump changing the values.
I'm sure others can improve on this design, but it suits my immediate needs...
Printed in PLA. Depending on your machine and slicer, supports might not be necessary.