...on two neck seal replacements. It went very well and is quite easy to do. I made the forms out of 3/8" plywood instead of cardboard, as I expect to be replacing the seals every few years and may do some for friends.

BTW, a good source for seals is OS Systems (www.ossystems.com). Their seals and booties are very high quality and are available in a broad range of sizes. The glue they recommend is expensive and noxious, but a little goes a long way, it dries quickly and it holds well.