You need a place to put your things, right? Do you have a pegboard? Do you have things that love flat surfaces? Well, then... here you go!

The STL file is set up for a 75mm deep shelf, 1/4 inch pegboard holes, and a 1 inch peg spacing. You'll need to edit the OpenSCAD file to change this.

If you don't like the defaults in the STL file, open this up in OpenSCAD, adjust the variables at the top, Compile & Render, then export as STL and reopen. Now you can print more stuff knowing you have a place to put it!

Once it's printed, you have two choices: put it into the pegboard while it's still warm (it will go in more easily but probably won't come out easily, and you run the risk of warping it), or let it cool, in which case you'll need a bit more force to get it in.