On the Higgin's plan - It shows that the author used 1/8 balsa for the bulkheads which I prefer to make the bulkheads out of 1/8 ply instead. There's many methods of making bulkheads straight from the plan such as using carbon copy (messy), 3M77 glue spray (also messy), etc...

Here's how I did with mine (Only showing how I made bulkhead #1)

1) Cut out all paper bulkhead templates with scissor...

2) Laid on 1/8 ply and marked dash lines all around the template... (Note: Its easier to do dash lines rather than trying to make solid line all around without moving the template in middle of tracing.)

3) Connected all dash lines... (Note: Dont forget to mark centerline and bulkhead numbers on it to make it much easier for yourself)