These hooks have holes for a 6mm wire. This is the diameter of the shelf wire used in Lowe's free-standing wire shelving racks. (The chrome or black kind, not closet shelving) Printed a bunch of these to hang doodads and small tools from the wire shelving I have in my garage. If you scale this in the X or Y axis, the hole will no longer be 6mm. Of course, you can use that to fine tune or change diameter. I printed mine at 60% fill and three shells in PLA. Plenty strong for hand tools. If you need instructions for this, it's a wonder that you can operate a 3d printer. Step one: Attach round end to shelf. Step two: Hang something on it. Step three: Marvel in wonder at the power of SCIENCE!!!!!!