I wanted to chime in on this thread and say that I like to get a winter DIY project going and decided to mess around with my tank this year. I want to make some rock work (not a background) but thought I should probably start by understanding the process by making something a bit less 3-d. So in an effort to make something as practice that may be useful, I decided to make a divider for the tank so if I have a need to separate fish or block off part of my tank I can do so. It works out to basically be two pieces of background siliconed together and I got some plastic mesh fabric from Jo-Ann's to silicone between them. The reason for the plastic mesh was so I can cut holes to allow water to pass through but not fish.
This guide is really good and the attention to detail in the small aspects of finesse helped to make sure that at each step I had work product that looked really close to Steve's. I really didn't have any additional issues or anything that was not covered in the guide. Thank you for the guide and well done Steve.
Here are some pictures of my finished product as viewed from both sides (I tried my hand at different rock designing on the different sides just to get a feel for how things work).
https://imgur.com/a/QwwCE
