Take 2 rolls: one will be the base, the other one must be perpendicular to the first one. Glue it on the edge.
I used hot glue for this process because it dries immediately and it's much faster.
Now glue another roll parallel to the previous one, then other 2 rolls on the other sides to create a "square".
If it's not clear enough, please take a look at the pictures, it's much easier to do than to explain :)