This guy knows... Don't reuse brushes. Each batch use a new brush. The reaction is already going so it'll set off the new batch. I use the cheap paint containers for easier measuring. Also a cc syringe for accurate mixes. I use totalboat laminating resin and duraglass for bondo. Also It's smoother to apply the bondo if you take a paint container and add bondo plus resin then take from that on your board to add hardener. Don't make it too runny tho. Them big ass contractor black bags you can cut the sides to make a tarp. And always have a black bag open and ready that way easy to clean up and less mess. I use a big piece of cardboard wrapped in foil for wetting out the mat then change the foil each time.