yes the supports are two separate pieces so it would probably hold a bigger sheet of paper, they could also be printed bigger. I used very thin a4 printer paper but a thicker paper could be used to add stiffness and reduce the light getting through.
As for the idea it wasn't mine but the design is a free design with no commercial restrictions so I could print and sell but to create these in volume they would probably need to be injection moulded so there would be set up costs. If I print sets individually then I have two routes to go, I can use a simpler design that's easier and quicker to print or the more complex ones that will cost more. Maybe I could sell both designs
the next big question would be how much would people pay for a pair of these?