I have fallen In love with these glass blocks. You can find them almost anywhere, for this project I bought them at Lowes they are 8 X 8 and run $4.97 each. (If you buy an entire case like I did you save a little bit)
To make the hat cut your felt 8H x 20L. On your short height fold it up about 2-3 inches it doesn't have to be perfect. glue the hat closed so it holds the flap in place, only place glue to close to the top of the fold in the back so now you should have a tube with a fold at the bottom. Do not glue the top closed.