Glad you decided to try it, Frogwalking. Like you, my engraving was unspeakable when I first tried it, and I just kept trying. After about 10 1"x2.5" practice plates, it was barely acceptable. Just keep practicing. You will get the feel for it if you do. I am still not a good engraver, but I am good enough to emulate some of the more mediocre makers of the period.
I must confess though, I do use 3/4" plywood for engraving flat pieces. On a curved piece, I usually use 2x4 spruce or pine. On the flat pieces, I usually stick them to the plywood with 5-minute epoxy. And like the Bondo, the epoxy releases easily once heated with a propane torch. The epoxy sets quicker than Bondo does.
On the other hand, epoxy is pricey compared to Bondo, and I do use Bondo for larger pieces like domed patchbox lids, where more fill is needed. The main thing you want is support behind your work, so as not to dent the piece, thus the fill on the domed lids.
As far as holding my work, I prefer to be seated when I engrave, and I am currently using an inexpensive machinist's vise to hold the wood, and just set it on my bench. This is by no means optimal, and I don't really recommend it. On really tight scrolls, I spend more time turning the work than I do engraving. But it works for me for now, until I get around to cutting a slice off one of my long-neglected bowling-balls and making my own ball vise.
And if you are doing wriggle engraving, as JTR said, it is much more efficient to use a push tool, as was traditionally done. A push graver, used in this manner, doesn't really engrave so much as swage the lines into the metal.
Hope we can see a picture of your work soon... That can really help identify things that you might be struggling with. I wish I had known about this forum when I started learning to engrave. Keep practicing, and good luck.
Matt
