I recently acquired a Yashica Mat-124G. As usual with vintage cameras, the light seals were rotten: gummy pieces of it were falling off.
Rather than shelling out the $10 (+ shipping) or so that some people are charging for replacement seals, I thought I would try to DIY. I found a blog post where someone had used adhesive-backed felt (available at most craft stores). So, I got some from Amazon since my local craft store did not carry any.
I cleaned out the old light seals with some Goof Off. Then, cut some 2-3 mm strips of the felt. I placed one, which went in crooked, so I ripped it off. Then I noticed all the lint. Just that small operation shed lots of lint. It was clearly visible on the cutting mat, and on my fingers. So, that was no good. I would not recommend felt. Maybe there is “photo grade felt” that does not shed? Anyway, I will be buying some bulk adhesive-backed closed-cell foam for the light seals. There are many listings on eBay, typically shipping from Hong Kong.