The quilt needs to be on a hard surface for marking. It doesn't work if you have the quilt in a frame; I found that out with using the Hera marker, If you want an indentation you have to have a hard surface under the quilt. I use a ruler and mark by rolling the blade along the edge.
These photos on the right and below show some of the marking and some of the quilting that is already done.
I have heard that there is a rolling Hera marker but have looked and looked on the internet and have not found one. If anyone knows where I can get one I would love to hear from you.
Now go and check out the rest of the good ideas.