to be honest i would just use a soldering iron. i'm currently repairing some motorbike fairings for a mate of mine who dropped his bike. ive just used a gas powered iron with a plastic melting bit fitted, to stitch the cracked bits of fairing back together. once ive done i will skim the area with plastic bumper filler (works better than car body filler as its flexible) then its just a case of primering and painting the panels back to their original colour.