secret

Don't tell your local composite supplier, but after a successful vac bag process, if you quickly pull the top sheet away from the mastic seam, you can re apply the waxed paper tape and with a little care, you can reuse the bag again and again.  Key to being able to do this is to lay additional layers of "used" bag or sheet plastic on top and bottom of your work so that the epoxy never really comes in contact with the outer bag........saves a little time and a little landfill space.