Craig Vetter's company used ABS plastic to make their fairings, I believe. The proper,
Hotcha repair kit runs around $80, from Craig. I have successfully used ABS Pipe Glue, from my local Ace Hardware store, to make repairs. The ABS Pipe Glue, is nothing more than ABS plastic dissolved in solvent: apply the cleaner solution, first, then apply the Glue (comes in different colors, thick, dries in 15 minutes). It can be sanded, somewhat molded/shaped (I used masking tape, which peeled off after the glue dried; wax paper won't stick, and would likely be a better option). It dries to a shiny finish, if untouched.
I repaired a crack in mine, applying the ABS Glue to the inside, filling in the gap (again, I used masking tape, on the outside, to keep it from oozing out), and building up a layer of reinforcement, on the inside, where no one will see it. I used this on the 1980's, plastic trunk I had, too. Worked beautifully. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII