Anal sex lovers will be interested in this handy masturbator, shaped as a nice asshole!
You will need a 3d print rubber/silicone with ability to stretch to at least 200%, I think direct extruder is needed to print such soft and elastic materials. If you don’t have one on your printer, consider using a mold to make this masturbator (it’s available in MOLDS category).
You should print it standing, back end to the bottom on the raft. Fill percentage and wall thickness will define the softness of the end product, so feel free to experiment with it.
Working length is 190mm, but feel free to scale the model to your needs.