Thanks Luke ... and others,
Just remember if you lay up your ply's its better to have them horizontal than vertical in the frame if its 'ride quality' your after. This makes it somewhat more difficult to build because a big sheet of ply lends itself to drawing out the profile of the bike, cutting it out and Bingo ... your riding in no time flat.
My first woody was built like that when on holiday in Japan with just a hand plane, a pull saw and a drill and i rode it all over the Japanese Alps. It was made by gluing 2 sheets of 3mm ply on each side to form a frame with natural wood infills top and bottom to complete the tubes.
It flexed when climbing and other riders said that the BB was swing with every pedal stroke on the flats ...but heck, it was lots of fun to ride !!
Its just an amazing feeling to make a fame and ride it over the mountains and into the distance...
The problem with this approach is when you want to go light weight and build stiff frames..
The laminated layers (ply's) need to be 'across the frame'. But frames being what they are, are only 40 to 50 mm across, so this is the place to get the most out of your laminates by including carbon or glass fibbers in the glue lines.
Also, If you start using natural wood don't rely on only one grain direction if forces will be applied directly along it.
As you can imagine laminating horizontally will brace against sideways forces of peddling and still by nature allow some 'give' to tame vertical road forces ...
All of this thinking 'maybe important' if you want to build 'light' and intend spending long hours in the saddle training, touring or commuting etc...
'Cruiser bikes' are generally under a lot less stress...so its a good place to start... and achieving a light weight frame is not an issue if your only trying to be lighter than the average Chinese frame ...
Also think about this saying ...
More of a good thing is not necessarily Better !!
Which for me means ...don't make EVERYTHING out of wood ...