I am no expert by any means on this subject. But I have installed enough foam in 35mm cameras to have discovered one valuable tip. Keep in mind, other people may have a better idea than mine. But mine seems to get me by on this tedious chore. The biggest difficulty in installing the strip foam in the back door channels is that the foam wants to stick to the sides. It's exceedingly difficult to get that sticky bottom of the foam to get all the way down to the bottom of the channel without grabbing at the sides. Moreover you need pretty high magnification to see your work. I use a 50mm lens turned around backwards, for lack of owning any other kind of magnifying visor or loupe. But that's not the tip which inspired this thread.
To keep the foam from constantly grabbing at the sides of the channel, I found that using ordinary rubbing alcohol, which is about 40% isopropyl, and a fine brush is very helpful. The object is something which will dry readily when the job is done, yet stay wet enough time to allow a little working time. Also the alcohol content is low enough to not have a solvent effect on the gum backing of the foam. Using water isn't what you want, because it may not dry well enough. And higher strength alcohol will dry too quickly and may even have a solvent effect on the adhesive.Once you close the back of the camera when the job is done, imagine any water down in there. could be a problem. Alcohol works very well for me. If it dries too soon, I just apply more. Between that and gentle stretching and relaxing of the foam to get it to get down in the channel all the way to the bottom is slow and tedious. I brush on a little alcohol, then gently stretch at the foam a little with one hand, using a toothpick to push it down in there. If it still grabs at the sides, you can usually pull it back up gently and not tear the foam. Easy does it. Take your time. It's usually 1/16 to 1/8 inch progress with each push with the toothpick.Sometimes you can get a whole 1/4 inch progress at the time before moving on.
To keep the foam from constantly grabbing at the sides of the channel, I found that using ordinary rubbing alcohol, which is about 40% isopropyl, and a fine brush is very helpful. The object is something which will dry readily when the job is done, yet stay wet enough time to allow a little working time. Also the alcohol content is low enough to not have a solvent effect on the gum backing of the foam. Using water isn't what you want, because it may not dry well enough. And higher strength alcohol will dry too quickly and may even have a solvent effect on the adhesive.Once you close the back of the camera when the job is done, imagine any water down in there. could be a problem. Alcohol works very well for me. If it dries too soon, I just apply more. Between that and gentle stretching and relaxing of the foam to get it to get down in the channel all the way to the bottom is slow and tedious. I brush on a little alcohol, then gently stretch at the foam a little with one hand, using a toothpick to push it down in there. If it still grabs at the sides, you can usually pull it back up gently and not tear the foam. Easy does it. Take your time. It's usually 1/16 to 1/8 inch progress with each push with the toothpick.Sometimes you can get a whole 1/4 inch progress at the time before moving on.