Warning: I stopped replacing foam light seals and started using black yarn on a customer's Nikon FM
A guy dropped off his Nikon FM at my bench in Sacramento with crumbly seals, and I had run out of my usual foam sheet, so I tried 1mm black yarn tucked into the groove with a tiny dab of contact cement. I figured it would fail within a month, but he came back 6 months later for a shutter issue and the yarn was still sitting perfect, no drag on the door. I always told people foam was the only real way, so this kind of flipped my thinking. What do you all use when you're out of the pre-cut kits?