Hello and Welcome to the board :D:D:D
We were discussing this in the chat room a while back. Looking at the ready made ones, we discovered that they used a more heavy duty shade to start with. It seems the springs and hardware are beefed up to help hold the extra weight of the batting and blocks/fabric :D:D:D
There are many permanent spray adhesive fabric friendly glues on the market that can be used to attach the flannel to the shades :D:D:D