[OXO cube]

this is the only UK supplier i ever found   Missile Products the UK's leading supplier of competition slot parts
in catalogue , under tools , part no :- 7090 & 7091
JaxonJig.jpg (1016×1016) (missile.co.uk)
LBJig.jpg (585×585) (missile.co.uk)

i am sure there will be other s dotted about , stumbled upon this one when browsing , by which time i had already bought a jewellers block and pins , so do not have a review of either product , perhaps others have used these ?
hope this helps 

Kev