I'm trying to put some props together, but coro here in the UK seems pretty expensive compared to some other markets - It's mostly branded Correx here... I've got a local print shop that'll sell me 8x4 sheets of 4mm for 12 (~$16) each, but I can't find 10mm for less than 40 a sheet (~$55), and that's only in packs of 5 sheets (and I'm not sure I really want that much ) I'm currently considering building with 4mm and supplementing with wooden frames on the back if I need to - Is that a reasonable idea?

So - Anyone got any better sources?

Alternatively, are there other materials that would be suitable substitute? Considered plywood, etc, but I'm concerned I may not waterproof it hard enough - Is it difficult to do effectively?

Thanks for reading this far - I'm attempting to get started here, and wishing I had easy access to Boscoyo shipping ;)