A 20 mm test tube holder for ant colonies. Print in vase mode. Bonus points if you print it in transparent red filament so you don’t bother your ants as much by viewing them.

Note: My printer has the slightest of elephants foot, the tube is a tiny bit loose in the holder up until the stand part. Thanks to the elephants foot slightly shrinking the entrance these are a near perfect fit. YMMV!