Retractable banners

Banners should be able to be rolled up with redstone. This idea heavily resides on the fact that banners look like curtains, but i think this feature could be used in castle builds and desert builds, both of which are very popular. I think it would also be cool (but not necessary) if you could use shears to cut a triangle into the bottom of a banner or even use a type of banner pattern to cut the banner into different shapes.