I would stay well away from the Thorns top bar hive it's rubbish and generally try and avoid composite woods like plywood because of the chemicals they can contain, that said I have and do use plywood to build hives and hive parts, but do try to use reclaimed wood rather than fresh stuff.
I was going to post links to the biobees web site, but that does not appear to be accessible at the minute, so here are some links to top bar hive plans that I've used.
http://www.buzzaboutbees.net/support-fil..._a_tbh.pdf
This one gives loads of info on Warre hives
http://wasatchwarre.wordpress.com/diy-beehive-plans/
One point I would make is that these hives are not that hard to build with some basic tools, I'm not a skilled carpenter by a long shot I'm very much a jack of all trades master of none, I've just finished building a new warre hive and all its parts for less than £50 and that's using new bought in timber so unless your loaded I would not go paying the stupid prices the likes of Thorne's charge.