Scriber part and piece of metal Free 3D print model

I think this is a genuinely useful tool.

I don't know if you've ever tried to cut a piece of wood to fit an irregular wall, but it's hard to gauge how much to cut out of it to match the wall.

With this tool, you can run the wheel up the wall while the pencil marks a precise line on the wood (or wallpaper, or cupboard, or whatever else you're trying to fix up).