Hi Clueless,
I have a stencil burner such as this that I used to cut/burn stencils for decorative painting (my life before quilting). Let me say that if the plastic or mylar you use to burn the stencil is thin enough it does quite well. But I tried it on some actual quilt stencil thickness plastic and it was awful. It burned through but not as fast nor as smooth as the thinner mylar and there were a lot of "joggy blobs" (technical term) going outside of the lines. Of course operator error had a lot to do with it I'm sure and with practice it probably wouldn't be as bad. I would definitely try it again! Oh and just a little tidbit here: I put my pattern on a table, covered it with a piece of glass (such as out of an old picture frame from the thrift store-nothing good, and wrap the raw edges with some masking tape to protect your fingers), put my mylar/stencil material on top of that and burned it out the pattern on the glass. Remember the burner gets really hot and the melted plastic is worse than melted cheese if it gets on your hands so be careful! If you have little ones around it's best to do it when they are napping or out playing. Hope this helps!
Heidi