Wow! A square skimmer! First time I'm seeing one!
I can't be sure... but I think there's a real reason why square skimmers may not work as well as round ones.
Something to do with turbulence, bubble movement, tensile strength of the body or costs of materials/extra work.
Alvy, our resident DIY guru may be able to shed some light!
But hey... good effort! It might work well! Looking forward to a product review!
AT