Sunken submarine model for an aquarium. I made it so little fish can get in (around 45-50mm in diameter) and it's a favourite hiding spot them. You need to put a little weight into the submarine so it sinks (a smal rock will do or if you have sand in your aquarium put a bit in the sub).
If you have any questions fell free to comment.

I printed it laying down (like it's placed in the aquarium) with supports.

If you like the design and use it, you can send me a tip :)