Sorry I've been hijacking this one cheers all for the tips and advice on where to get the trim from i'm redoing a dormobile roof section the original was a white painted / covered mdf type material which is knackered and I'm thinking birch would look nicer with some ally trim strips....
Found @ 3mm ply but guess the 1.5 mm stuff would be the biz, severn ply do this for anyone around Bristol SWALES etc.