To add to Jack's post:
1) I used 4' by 8' bendy birch ply--had it shipped to Florida all the way from Massachusetts (
www.boulterplywood.com). It bends the way you tell them you WANT it to bend, and since most of us want a 4 by 8 sheet to bend the long way, the 1/8" stuff can actually be rolled and placed in a mailing tube 4' high.
2) Boulter had it in 1/8" or 1/4". I used 1/4" for both the roof and cabin ceiling because they were out of 1/8", but 1/4" WON'T bend into a tube. So it was shipped flat to the Fedex station 20 plus miles from me because FedEx won't deliver like this to a residence. (I had to pick it up.)
This was done at a big loss to Boulter, because the guy was drunk, he knew I was also drunk, and he didn't want to deal with me any longer. My three sheets were sandwiched between two pieces of flakeboard, which I ALSO used for my build, so that was a bonus.
3) The 1/8" bendy is WAY bendy, and you don't have to go this thin. Tom S (Swenson) noted this for the piece he used for his cabin. It was too "wavy." The 1/4" will also bend to just about any imaginable radius.
4) If you're skinning with aluminum, painting or epoxying, just forget all of this crap and go with the cheaper Luan if you can find it in the size you need.
5) If you want to finish with spar urethane or other like I did for that nice birch grain, be aware that number 6 below may or may not be true:
6) My roof came out beautifully, but bent the OTHER way for the cabin ceiling--no.
So as Jack said above about the rough side, I think that only ONE side is rough. Remember that this bendy stuff is used to make all kinds of curved cabinet work where the OUTSIDE of the bend is meant to be visible. And I can't swear on this but I'm pretty sure that it only bends one way. I just don't remember. (So I think it only bends one way and I know it only bends in one direction.)
I'm also not sure if my cabin ceiling came out like sh** because I'm a shitty builder and I didn't sand well enough with the orbital and do everything properly for all of those coats--but this MAY be the case, since Tom's came out great finish-wise, athough he experienced that wavy problem from using 1/8".
Anyway, everything is fixable and doable, and all I did was wind up covering my cabin ceiling with tiki bamboo, which is what I should have done int he first place.
A HELL of a lot easier that all of that thaning and sanding.
Remember--style over substance.