The executive summary is the comments on the pictures. Anyone who is an accomplished carver will probably not need to read the additional commentary below.
This method evolved for me as I attempted to get high relief with a minimum of effort. I learned that it was important to keep a vertical profile surface (no undercut) while the carving was evolving. As long as the profile surface remained vertical adjustments to the horizontal surface to correct the plane could easily be made without affecting the final shape. One of the most profound changes in my carvings occurred when I realized that the uninspiring look was flatness. I needed to change the plane on every surface I could to the greatest degree I could and the result was very satisfying. Now I continue to refine the carving surface until I am satisfied I have achieved that goal. Delaying the undercut until this point was an important lesson to learn. Although the same thing applies to other relief carving methods sawing the profile with a scroll saw was the easiest way for me to achieve this initial state. As a result this method evolved.
Of course selecting a good matching piece of wood for the carving will make for a good matching appliqué that could easily pass as an in place carving. I have on some projects taken a slice off the part to which the appliqué was to be attached in order to get and exact match. I can honestly say that not one person noticed the exact match, not even my wood working friends, so I am not convinced it is necessary.
The steps are as follows:
1. Select and paste a copy or outline of the subject on to a matching piece of primary wood. Start with a piece about ½ inch thick (plus or minus ¼ inch).
2. Scroll saw the profile inside and outside with as much detail as you want in the final piece. I usually include the zigzag leaf pattern in this detail.
3. Glue the cutout to a piece of plywood and mount it on your carving vice or work table. See photo A.
4. Carve the top surfaces to suit your vision of the drawing. Be sure to exaggerate the changes in plane (e.g. the direction each flower is facing) to ensure it is not flat looking. When the surface is done to your satisfaction you can add any additional detail like leaf veining.
5. Slice the piece off the backing using a pull saw or a band saw. You may have to saw off part of the backer board in order to preserve the full depth of the carving. See photo B
6. Undercut the back side to about 35 degrees but be sure to leave some of the flat glue surface for later in order to ensure a good adhesion of the appliqué. The cutter used in this process will usually leave a rough surface and is stressful on delicate parts. Avoid doing the thin or delicate parts at this point. Working on the back while viewing from the front or back allows you to get at every area you need to do. Careful low pressure cutting will be necessary. Be sure to ware protective gloves until you have mastered this process. See photo C.
7. Finish and clean up the undercut with a fine ruby cutter. This cutter will leave a sanded like finish and can be used to do the undercutting on the delicate parts as well. See photo D and E.
8. Now you can glue in the appliqué and apply and finish to your own preferences. I use shellac in all cases to ensure the stain does not go too dark and ruin the depth and detail in the piece. See photo F. and G.
Questions and comments are welcome.
P.S. If breakage occurs, just mark where the joint should be with a small piece of masking tape (so you wont accidentaly grind if off during undercutting) and when all undercutting is done lay it flat on wax paper and glue back together. This happens all the time on fragile cross grain situations.