Hermit Crab Shell House

The orientation is fixed in the smaller shell for better printing, I printed with a 6mm brim with supports, I did have to dremel out a small section of the internal shell. The size is scalable but I have yet to try printing a smaller version. Battle Shell most likely needs to be scaled up to whatever size your hermit crab needs.
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/dQDFZJA7aw8