After rummaging through my caps box I did find 2 caps that kind of fit, one is original FED and it's the right size but it is a bit loose on the I-26 lens... I think with some ingenuity you can get it to fit, maybe put some rubber liner or something inside.. another one is from U-23 englarger lens that fits pretty good, but i's an odd shape, it's a bit deep but it has felt lining inside that makes it stay on Zarya lens pretty good.
Let me know if you want any of these, I can ship them to you in a few days when I'll be at post office. Email me directly with your address then at vladkern@particle-z.com.
LOL, no sorry, I don't even have that camera... but I'm sure I can find something that fits.. I have a Zarya in my collection and I could try different caps on it.. if you tell me dimensions I can look