This is a modular wine rack - most wine bottles (75cl) will fit into it. Print as many as you like and stack them. Can also store other objects like small towels plastic bags, liquor bottles etc.
They simply slide into each other and will hold each other in place when a layer of 2 is stacked.
Make sure to print it vertically for the best tolerance on the rails. I've used support under the rails and flipped it. This means that no brigding is required.
You might require to use a knife and trim away a little bit of the material after the rail, so it can fit nicely into the slot on another piece.