IKEA's Ivar system has horizontal cross braces on the vertical pieces. I had some stuff that was in the road, and I wanted to fix that, so I designed a simple little lightweight hook that could hang over one of those cross pieces, and hold some stuff for me. In this case, I was trying to get an airbrush hose out of the road, so I needed a hook with a bit more depth and height than the other options I'd seen on here. The whole thing prints in a few minutes and requires no supports.