Another trick I stubbled on is to run the plans thru the copier in small sections 8 1/2 x 11. this minimumizes the distortion that seems to be ok at center, but grows toward the edges.
I set the darkness to maximum to get the max ink on the copy.

Then I cut and tape for the longer sections.
Now, get mama's steam iron out while shes away.
Put the photocopy, ink down, on balsa and iron away.
Ink xfers to the balsa, leaving a perfect trace to cut out parts.

Don't cut the originals, especially if they are borrowed.
I have good luck using wax paper as 'Plan Saver'. jet