When I was remodeling my Kyokushin Karate Dojo, I needed some simple changing rooms for the students. I wanted them to be easy to put up, and ideally make it so they would stay clean and tidy. After thinking about it, the KALLAX seemed like a good fit. The process was fairly simple. First we made a simple frame out of 2×4 on the floor to raise the KALLAX up a bit, and to give it somewhat of a built-in cabinet look. We mounted then 4×4 KALLAX to the 2×4 frame and the wall. Next the 1×4 KALLAX were put on their side above the 4×4.*
Once the KALLAX shelves were in place and secured to the wall and each other, we applied the birch plywood backing. This gave privacy to the changing area, plus a nice place for people to sit against on the other side. We added plumbing pipe to create a curtain rod, which had the added benefit of providing stability/ridgidity on the free-standing end of the KALLAX.
*The 5×5 would have been a good choice as well, but the length would not work for our scenario. Certainly, cutting down the 5×5 to be a 5×4 was an option, but going with a 4×4 + 1×4 was quicker and easier)