These pics are in my 180g build in Large Reefs forum but thought i'd put a few shots here as the DIY rock wall is applicable to any tank.
Lots of detail in the build thread (180g UK Reef) but here's a few pics ....have to say, having gone through cement rock, reef ceramics, etc , etc - this is the best i have done and wished i tried it before!
Cable tie real rock to crate:
Foam it:
Trim foam, cover foam in epoxy resin and sand and crushed coral:
This is 3 bits so far:
This is the way it will look when done (covers the weir in the corner and 3 islands in the center:
This shows how much i've done and whats left to do (the blue bits)