Comingled recycled plastics can be made raw into RPL - recyled plastic lumber. This works if you don't harvest out the LDPE that makes up the bulk of the waste stream. The LDPE (and HDPE) act as binders for all of the other plastics, even the odd bit of thermoset that might get in there (unmeltable plastics). If ground up fine enough the containments just act as filler. How do I know? I designed such a system for a bid for the US Navy in the 90's as part of a clean-wake program for ships.