This solder holder is designed to be mounted on either a wall or the underside of a shelf. I designed it to hold a 1lb roll I had that is 75mm long and has a 20mm hole in the middle. I left a little wiggle room in the dimensions so it should work for other similar sized rolls as well. There are 2 versions, 1 with more straight edges and 1 with more curves. Functionality and basic dimensions are the same, so just print whichever one looks better to you!