Step 1: Make a rubbing of the surface to be engraved
Affix the paper to the surface to be engraved. I used single-sided tape stuck in a loop, but double-sided tape is less likely to move. Rubber cement would work fine too, I'm sure.
Using a graphite pencil, lightly rub around the edge of your object. This should transfer the outline of your object onto the paper. Use the side of the pencil when making the rubbing, not the tip, or you'll just poke holes in the paper.