The next step was to start on the back rock wall. I actually started it while waiting for my glass to come in and the measurements turned out pretty well.
I started with the plastic lighting egg crate cut to size, joined with zip ties, and attached a base plate to help hold it down with live rock once it is foamed and in the tank.
I had previously given 3 pieces of old base rock a good cleaning and multiple freshwater rinses. I then smashed them up into suitable size pieces with a big hammer and gave them the high pressure hose treatment and set them aside to dry. Essentially I created small dead rocks from big old live rock. Here's what they looked like before and after.
I then went about drilling holes in the rock big enough to push a zip tie through (smelled just like the dentist drilling a tooth!). I attached the rock to the egg crate using the lightest pieces of rock towards the top. The egg crate at this point is very flimsy and needs lots of support not to break. When closing the zip ties it is important to have the catch in the front and not the back of the egg crate. With the catches in the back it makes it difficult to get the egg crate to sit flat against the aquarium wall. I left enough space at the bottom of the vertical piece of egg crate to allow the placement of live rock up against the wall on the base plate. Here's what it looks like at this stage.
More to come...