For mine, I used plastic epoxy to glue things together, held in place while it cured overnight. I reinforced the seams with E-6000, and used plumbing epoxy (which sets up like concrete) to back off the vents and reinforce some of the other joins. Important thing is to sand down that shine. I did a lot of work with 220-grit sandpaper to give the adhesives, putties, and paint something to bite into.
[ETA: My WIP thread can be found at CTdotN, cross-posted to Mando Mercs -- and formerly C-E.]
--Jonah