Mini-caves!

I've been meaning to do this too but haven't decided the medium I want to use. I'm torn between a 3D printer, epoxy resin and gypsum cement. You did a nice job! How did you make yours?

I use hot glue. Make a hump of wet sand in a bowl to the size you need and simply coat it with hot glue. Let it cool for a few, then cut a doorway, solder it a bit with the gluegun tip to smoothen for aesthetics check for holes

Though i also sometimes mimic a 3d printer myself

I've seen a lot of people get creative with hot glue. I even bought some from Hobby Lobby that were opaque colors. Pretty cool!