This is V1 of my adaption of the Snap-On MAGBOWL. I have a V1, V2(Here), and a Strap-On V2(Here). The V1 and V2 use 40mm x 10mm x 5mm magnets. Available from amazon(Here). Each tray uses 4 magnets and holds very well to whatever you stick it on. I use them daily in a shop environment for lug nuts and studs. They can be printed out of any material you like, I use print them out of PLA plus/pro and PETG, they hold up great. Use my included printing profiles for best results.