Well, Super glue or 5 min epoxy would be good for putting the sintra pieces together.
Bondo is a 2 part catalytic body filler used for car body work to fill dents and holes.
Its a styrene based putty and when you mix the hardening catalyst to the putty agent, it hardens in bout 10 mins after applying. That is what everyone uses as a seam filler smoothing agent on their gauntlets after glueing them.
Hope this helps a bit with your defining of pieces spiffy.