I first spotted this cool pop-up bike basket at ICFF last year. It's made of steel alloy containing up to 40% recycled content (and also fully recyclable) with a low-VOC powder coating. Ships flat, and can be installed on either the front or rear of any bicycle. And it's super sturdy!
Measures L15" x W10" at the top and L11.5" x W6.5" at the base. The steel is 0.1" thick.