These are very nicely made - I don't have the time/tools to make my own.
However I've found that they (and clamp type mounts in general) require modification for some motors - sometimes the clamp will have to be relieved to clear the NVA and on Fox type three bolt backplates the overhang will require some mods to the clamp to fit.
I've used them on my two Ukeys - the 40 now has an OS Max S 35 and the 35 and Enya 35.
Tony 'buildem,flyem,crashem,mendem,flyem' Elmore