Not got time to look at those links now - about to go into school to make a few bits I can't do at home :)

Try this site for epoxy:
http://www.ecfibreglasssupplies.co.u...k/default.aspx

Maybe reinforce it with some of there glass/carbon fibre?

I've sortof assembled mine with just the box section as it is...and it seems ok. I'll have it assembled properly later on today, then we'll see!