You may want to make a paper trace of the patchbox. That will lay on the wood easier (flatter) than the actual metal parts and will give you a start. It will make layout easier too.
A sharp tool is used to trace around the paper. If you're uncomfortable, use a pencil and draw your line. Then you use a sharp tool or chisel and stamp the outline. On the curves, if you don't have a chisel that conforms with the curve, use a sharp knife (or Xacto blade). Once your outline is cut down to the width of your metal so if the metal is 3/32, try to stamp down that deep. If you can't go that deep, it's OK as you can always go back to that spot after some wood has been removed. Don't go too deep but if you do, that can be filled in. Stop short of the ideal depth and use a scraper to make the inletted surface level. You may have to make your own scraper (a small piece of metal that is sharp) but that's easy.
Be sure the stock is mounted in a padded vise so it won't shift.
Have plenty of light.
Vigilantibus et non dormientibus jura subveniunt. Molon Labe!