So the kiddos lost their caps to their toothpaste. Whipped up a quick replacement that I thought might be handy for others. Pretty simple only uses 1g of filament and prints in under 20 minutes total time. Has knurled edges on the outside to make gripping easier.

I tested this with the Kids Crest Toothpaste. The inner diameter is about 11.6mm with a 2mm thread pitch. If your toothpaste requires a different pitch or larger or smaller hole, I do have the STL file uploaded for you to modify to fit your needs as a starting base. Cap height in total is only 10mm so quite compact. Threads are cut into the wall of the cap, so no fragile threads sticking out to break off. Can be easily washed and reused multiple times!

Anyways, just print it with the top down, threads up, and you shouldn't need to do anything else. Should come out great! 

Might be a little tight the first time or two to screw on, but loosens up some and fits great on the appropriate sized toothpaste containers.