: I have read that MDF is the best for making forms. I have read that plywood
: is all you meed. I have read that the cheapest plywood is the best. Use
: 3/4", double it up and use 1.5" etc etc.

: What material would you recommend for a first time Stripper building the
: Great Auk?

Both ply and MDF can be used quite satisfactorily.
MDF is sometimes said to be not as good at holding staples because it tend to split. I wouldn't know. I haven't used staples on any of my kayaks. The shape of the Great Auk means that you would not need the staples to have a lot of holding power anyway, so MDF would be OK.

I would never use anything as thick as 3/4". I have used 9mm MDF, 13mm (1/2") ply and 16mm ply (5/8") and have had no problems with any of them.

The end stems need to be thicker than 9mm unless you add some braces because unlike the other forms, the forces applied by the strips can make them flex.

I generally just use whatever I have lying around the place. If I had to go and buy something especially, I would probably get 1/2" structural (cheap) ply.