I want to start 3D printing dice towers, but how do I model + print the inside of one?

Hello! So yes, I want to model and 3D print my own dice towers for my own (and maybe for selling) D&D games. I have the outsides in mind, of course, and even the basic design of how the inside where the dice actually roll should function, but I'm worried namely about supports being printed on the inside and being unable to remove them in a fully closed box or cylinder.

I looked online for any model files someone else may have made for use that are just the guts of a dice tower, but no luck. I do plan to make them fairly large (the idea to make my own was inspired by Dimension 20's Box of Doom and the fear it struck into the players every time lol) between 20cm and 30cm tall.

So how would you/should I go about it? Should I have a lid on top that could be placed on after removing the supports? Should the inner "steps" for the dice be textured some way for extra rolling potential instead of just slanted to hit one another? My design for a cylinder was using a spiral staircase shape while a square has platforms to bounce off of.

Any tips are super appreciated! Thanks!!