I'm not sure what you are asking- But if you want to copy the plans onto balsa, you can-
1 Photocopy the plans then place them on the balsa (upside down) and use a clothes iron to print the plans onto the balsa.
2 Or you can simply stick the plans to the basa and cut around the shape you want
3 Or you could place the plans over the balsa and use a pin to prick out the outline of the part
I hope this answers your question