I keep a few guitar pedals with a small practice amp in my office to take a music break. I wanted to keep things out of site but accessible. I simply installed the KALLAX door insert Vertically. Not the back and sides just the door so the door would fold down onto the floor. I covered the door interior with industrial Velcro and Velcro-ed the guitar pedals to it.
When I want to play I simply fold down the door and plug in the guitar. The cables run around back and into the small practice amp in the next KALLAX cube.