Thanks for your reply and advice Aqua360, after a lot of messing around with different layouts I stayed with the one in the photos. They don't really show the layout that well but there is plenty of swimming and viewing space.
Hi Cadfiel, sorry for the delay in replying, the black mesh stuff is 'aquarium egg crate', there's lots of it on ebay, reefers use it a lot.
The plastic support tubes are just plumbing overflow pipe cut to length with corresponging grooves cut in for the egg crate to sit on, I used a Dremmel with a cutting disc but a hack saw would also work. The egg crate is easy to cut either with scissors or wire cutters.
I used them for exactly the reason you mentined, I too don't like the idea of rock sitting directly on the glass.
Hope that helps.