Let me preface by saying that this is not my idea. I was mining Youtube for information on "Lost Wax" and this was an incidental in the video. As soon as I saw it, I recognized its utility in our community for everyone that has limited tools and resources and are by necessity restricted to coping saws. It works very well and is simple to make and a lot cheaper than vises.
I hope this helps someone.
Thanx for Lookin' & Happy Shootin'