Great. I will make them to the exact measurements of my plastic rings, that fits very tightly. If all goes wrong, I would guess I just need a bit of sand paper to remove dirt/corrosion in the wheels.
Thanks Chris, I'll check how far I can extend the spigot into the wheels.
I'm not 100% what you mean with the taper, but I'm guessing you are talking about the angle laid in from the base of the spacer towards the spigot, right? It was a recommendation from the guy who makes them to make them as strong as possible as there is only 67-60.1=6,9mm connecting the "spigot" part to the spacer. He emphasises a way to do it was to use as much angle as the wheel would allow. So we modelled it after a plastic spigot ring that fits tightly to the wheel.