Peter - thanks for the great info. Will you send me your pin-reg carrier as a gift??? Come on!! I know you're a nice guy deep down!! Just KIIIDDINNNNGG of course! Anyway - it's interesting - I was also actually thinking of a means to obviate or bypass the use of glass. Some sort of tensioning mechanism that pulls the neg tight across the opening, especially as the neg starts to expand. Perhaps I should look into other areas of technology where this is a desirable requirement - medical? trampolines? I dunno. If I figure something out I'll try to publish it here first. Though I'm sure glass is probably the best route. As for the manual - so you would recommend that, eh? I wasn't sure how useful it would be. Many manuals aren't all that great from what I've seen. But I'll take your word for it. KHB in Canada has them for USD 20. Perhaps I'll order one.