I just use tracing paper. Trace the part with a soft pencil, flip the paper over & run over the outline with the pencil on the back of the paper, then turn it right way up again, place it on the wood & run over the outline again.

Sort of like home made carbon paper. It's convienient to buy the paper on a roll at the supermarket as greaseproof paper.

Flew in a Turbo Porter to a NZ glacier during a recent holiday, great experience! - John.