PET!

You can get PET in various forms (sadly, I don’t have a good local supplier, but you should try talking to TAP plastics)—including quite rigid sheet. You can make PET from plastic bottles, so you can use recycled materials and then recycle them into the regular blue bin stream.

Hi Ben! Thanks for answering
So the next big question is: can you put unmarked PET scraps into the blue bin , or do they need the little recycling symbol with the number?

Not a clue—but you’d be better off taking the scraps directly to the recycling center for sorting, if you have a large quantity.