Continuing the discussion from Cutting a poly cutting board:
Just found this TAP Poly-Weld Adhesive for bonding Polyethylene.
From the webpage:
TAP Poly-Weld Adhesive: Imagine being able to structurally bond Polyethylene!!! This has been virtually impossible in the past. Now, with a simple flame treatment and Poly-Weld, one can create strong joints on Low, Medium, or High Density Polyethylene.