I built these mounts to fit two full size spools of filament on the Hands 2. Since they were colliding in the default area. Aka the back of the top rail between the z-rails which is not enough space for two full spools on a Hands 2. And mounting them to the front risks making the spool holders a obstacle should the extruders get that high. This probably only an issue for the Hands 2, being the smallest Tenlog machine. Of course, these mounts could be used by any 3D printer with the same size t-bar and spool holders. I just don't know which printers, so they weren't added to my description. For the spool holders I used M5x16 bolts (but you can use M5x20) with M5 nuts. For the mount to the t-bar rail I used M5x8 bolts with M5 t-nuts. The parts were printed at 90% infill, gyroid.