[OliSharp]

I made one with parts from eBay and Amazon for about £5 using:

car wheel nut M12 x 1.5
bolt M12 x 1.5 and 120mm long (don't go shorter than this)
ten steel repair washers M12

NB the M12 thread is a fine thread, if your nut isn't going on easily don't force it, you may have the wrong size.

Given the low cost here I'd very much recommend having one on hand before you start an injector replacement job. Speaking from experience it's very frustrating taking all the engine covers off and then not being able to get the injectors out!

photo here: https://flic.kr/p/2g8zSXB