I made this modular shelf since my table is a mess. I made it strong, because I store some expensive tools on it and I don't want it to break them for being too weak.

The shelf system is modular, so you can expand it to be as wide as possible. You cannot lock it in place if you stack them on top of each other, so for now, it is only expandable horizontally. A version that can be expanded both ways might be coming as well. You can use 0-3 shelves per section, although a shelf without shelves is not really a shelf, just a shell.

Depending on how strong you want it to be, you can add walls and infill, but with my settings, you save a little filament and time (0.6 mm nozzle, 2 walls, 10 % infill).

I made it with PETG, but PLA should work as well.

This requires no external hardware or glue, only the connectors that are printed. Simple to put together, push the dowels into the walls and the shelves into place. The back support is for extra support in the back. If you have trouble putting it together, look at the GIF. If you still have trouble... I have some news....