The advantage to using your mold Dave is that you can cut the contact paper a bit larger and use the weight of the mold to hold down the edges. I have found that sometimes the contact paper wants to curl up on the edges. If that happens, i spray some PAM cooking spray in the mold before putting in the contact paper. It acts as a temporary glue to hold the contact paper in place until the concrete is put in. Off course it also helps to release the stone after curing.
