There is a way to minimize all the dust with this little trick:

• First, mask off the boundary where you want the finished edges of the fiberglass tape to end. Normally I would use 2" tape for bonding the shells, so do the masking 1" (2,5 cm) on either side of the sheerline seam.
  
  
• Now use the next wider tape. Here I am using 3" (or scraps of leftover fabric if you want to save $) so that the salved edges overlap the masking tape by 1/2" or more. Epoxy everything down and let it set until the next day. Slow setting epoxies work really well because the next day the material will be still very pliable. Do not use fast setting hardeners alone for they are too brittle and tend to shatter when bent, scraped or cut.
  
  
• Bend the edges of the tape, together with the masking tape up to the masked boundary as in the picture.

• Slice (score) the fiberglass tape at an accute angle with a sharp knife, avoiding contact with the underlying fiberglass or wood. It is easier than it looks.