I went to Tinkercad.com, and about thirty minutes later this happened. Its shaped like boobs. :) Why not? Fidget Pop 1 is hollow all the way thru, Fidget Pop 2 has an air pocket for a nice squishy feel. I recommend printing Fidget Pop 2. Both have a hole for keychain. Its made to be printed in TPU. I would recommend to print them individually, to help prevent stringing.
The author hasn't provided the model origin yet.