Molded plastic is a difficult plastic to repair because it does not bond easily and therefore does not glue back together. It requires a little extra work to fix or repair the molded plastic item. Even plastic adhesives are not always enough to keep it together and fix the problem, but there are ways to repair the plastic and avoid expensive purchases.
Pull the plastic back together. Hold it so it is shaped properly. Have a friend or family member help, if necessary, for larger items.
Clean the plastic with a cleaning cloth and a solvent. The solvent is a type of soap that removes dirt, oils and anything else that would create problems for bonding.
Sand the plastic with 200- to 400-grit sandpaper. Sand until the plastic is smooth and there are no rough edges.
Add flame to melt the plastic edges. This will make bonding easier. The size of the molded plastic item and damage will determine the best tool for adding heat. Small items need only a lighter, while a larger item will need a larger flame. Allow about one to two hours for the plastic to start cooling.
Apply a clear epoxy to the plastic material. This will keep it together and bond the plastic.
Add a patch. The patch will differ based on the specific item. Some will use a fiberglass patch, such as a molded plastic boat, while other items might use plastics or small pieces of molded plastic. The patch is added to the epoxy while it is wet so it will bond and dry. For large patches, add a few layers of epoxy and patch.
Sand the patch until smooth.