I use those "Sooper Clips" from Grimco or Fellers. I kind of felt like a tool buying them, but I don't have time to screw around making my own. They actually work well for almost everything (except full rolls of banner).
Just buy them and move on to your next Signs101 question.
http://www.grimco.com/Products.aspx?cid=0978&pid=13562
Takes no TIME to make your own, because you don't actually make anything, get the roll of Velcro, and cut off a piece, that's it, nothing to it! Takes about 10 seconds.
The Velcro tie straps don't coast anywhere near as much as the plastic clips.
The Velcro tie straps never leave a mark on the vinyl like the clips do when pushing them on and pulling them off.
The Velcro tie straps never break like the plastic clips can if you try and force them on to a large roll.
The Velcro tie straps fits virtually any size roll, including large rolls of banner material, you need to order different size like the plastic clips.