I've got a set of MM castors on some homemade skates for moving machinery
Probably about 5yrs old now but have moved several lathes that were around 750kg, a few milling machines and a great big heavy hydraulic press that I collected for @God mode restorations
Still working well, currently got a big scissor lift stacked on them so I can move it around the lockup till I get the slab done
