If I need the help, I certainly will take you up on the offer. And you're right, I suppose it's not that hard, but I was glad to get some of your input. I think I'll take your advice and resin each layer of cardboard before assembly, and I might even try to modify the pattern to include a skeleton of wooden dowels to keep it nice and rigid. I'd also like to pay some attention to getting the rounded sections actually rounded (which I'll probably do by hand, so maybe I can find a way to temporarily assemble it and sand out some of that shape before I resin it).
How would you say the weight and feel are? Does the weight feel like it's made out of cardboard, or when you grab the handle? If it's really light I could consider finding a way to weigh it down, but I don't need it to have the heft of an actual rifle (I just don't want it to feel like it's *actually* made out of paper, like one of those hollow plastic toy guns). Other than that, there's just a little bit of creative liscense I'd take with the suppressor (I've got some appropriately-sized PVC that I'd just need to make a cap for) and the sight (not too difficult). I also liked your concept of including actual screws, it's little things like that what give it a realistic flair.
To be honest, the only part I feel like I haven't got figured out is the ammunition counter and bolt. Yep. I know they make kits for the MA5-series ammo counters, but I wonder if anyone has ever made one for a DMR, or how difficult it would be to make such a system given that I don't really have any of that sort of electronics experience. Then again, I don't really intend to have a functioning trigger, and the bolt was just going to be a spring loaded little lever, so maybe I could just put some LEDs behind a stencil that makes it look like there's a functional counter. It would always show 15, but whatever. Probably hide the switch for it in the mag well or something.
Thinking ahead of time, though. It'll be a while before I attempt to tackle this. I'm somewhere between a perfectionist and the ambitious type. Thanks for all the great input, though, and I'm glad you ended up with a badass final product!