Newer versions (not yet on thingiverse) have the 1/8" walls instead of 1/16th and have been redesigned to secure with self-tapping screws, so the receiving boss is now much, much thicker with a smaller hole. Also, the boss in the back now has a full “pocket” so that the two sides can be secured with a 3/8" screw instead of a 3/4".
But I don’t have any ribs or other structure for stiffening. There’s not really going to be any stress on anything once it’s assembled, it’s just going to sit on a shelf. The issue is that the pieces I print just aren’t fitting together properly and I’m wondering what I’ve done wrong.