Busted sheave, odd size, what to do?

[hd002e]

At the end of my z-spar boom is a casette of four sheaves that are used for outhaul, reefing and the topping lift. The sheaves are as old as the boat and the black plastic has cracked. The other day my reefing line got stuck in the opening and gave me a bit of a hassle as I couldn’t reef.

The size of these sheaves are kind of odd:

OD: 44mm
ID: 8mm
Width: 11mm

I looked up mauri pro and a few other rigging suppliers but no one seems to have the exact size. I am thinking of having them machined out of Delrin using a lathe.

My questions are:
- what is a good place to find sheaves?
- is Delrin a good UV stable material?
- should I get them machined out of stainless steel instead?

Thanks!