Currently using 3mm (1/8th") Luan. $14 a sheet. Lightweight and the outer plys are not as thick as the inner. There is only one "pretty" face, so needs to be planned while cutting. Found two voids totalling the size of a thumb end in three sheets. Strength remains to be seen, but it will be glassed inside and out and will be treated with a bit more respect than the 4mm hardwood laker which was also glassed inside and out. The Laker is very strong, which made me feel confident in going lighter on this one. Aiming for mid thirties (lbs) without accessories. I suppose the type of boat you intend building will dictate what you should or should not use.
Builder show and discuss their progress.