Terraforming Mars player mat holder (stackable)
I had printed another player mat for this game, however, it didn't hold the paper player mat and people (me) can be clumsy. The tolerances for the cubes are fairly tight, but they seemed to work for all players.
There are two options for printing, IMHO, either with a bunch support material where the paper mat goes. Or flip it upside down and deal with messy-ish numbers. I went the messy numbers route. We'll paint it though to make it a bit cleaner.