AC, lemme give you another tip that is EXTREMELY helpful for those of us with 'fat fingers'...
Get yourself a mess of those little 'hemostat' clamps from the hardware store, or better yet, when one of those big 'Homier' or "Cummings Tools" truck tool sales come to town. Don't buy them at the hobby shop; they're REALLY screw you on the price, though the hardware store is often fairly inexpensive on them. They look like little bitty long-handled scissors, and they make PERFECT clamps for this sort of work, ESPECIALLY making paper (and by extension plastic) transitions from sheet materials.
I bought about 8 or 10 of the little buggars for about $1 each at various sales and stuff, and they are EXTREMELY handy! The only thing I didn't like about them was the serrated jaws-- they would emboss a rather ugly serration mark into softened glued paper, but I fixed that easy enough-- I took mine to the shop and gingerly ground down the serrations until the jaws were smooth. One could accomplish the same thing with a Dremel tool with a cutoff disk or sanding drum installed, or even a good file and some elbow grease.
Last tool sale I went to I picked up a set of dinky plastic clamps in various sizes/shapes, a package for like $6 for 10 clamps, something like that. I also LOVE regular old spring clothespins-- pick up a pack next time your in the hardware store-- they're very handy too.
I've been building a LOT of Dr. Zooch kits and virtually ALL of his kits use paper transitions for things like capsule wraps, stage transitions, and engine bells, antenna canisters, etc. Once you get used to working with the stuff and choose the right glue (NOT CA) and have the clamps to help you 'hold things together' til the glue sets, you'll be amazed at how much you'll like paper transitions. Sounds like you've had some problems with paper transitions and switched to styrene thinking it would solve all your problems, when actually FMPOV the styrene is probably actually making them much worse! Thing is, when you're making transitions out of flat sheets of material, no matter what the material is, you're having to fight the natural tendancy of the material to 'lay flat'-- you HAVE to use some sort of clamp (even your fingers count if you're not using anything else) until the glue 'grabs' and can hold the pieces together against the innate strains inside the material trying to spring apart and 'lay flat' again...
I use white glue on paper transitions if they're less than about 2-3 inches long (as most are) and then when the glue is dry, I HARDEN the transition with CA, which soaks into the paper and bonds all the fibers together much like fiberglass, making the transition VERY smooth and tough compared to regular paper (be warned though, do this outside as the fumes STINK! and also, don't do it to paper wraps-- the CA turns the paper a bit 'translucent' and it's fine for painting over but will ruin pre-printed graphics on the paper.)
For longer transitions, you really have to use rubber cement or contact cement to bond the seam, because the white glue tends to make the paper 'wavy' and warped from the water in the glue swelling and softening the paper. Tim Van Milligan produced an EXCELLENT tutorial video on YouTube awhile back dealing with paper transitions-- go to
www.apogeerockets.com and look for the links to the video tutorials.
Good luck! OL JR