This idea is inspired by this one: http://www.thecatshouse.com/
Step 1: Stuff you need
1x2s from Home Depot are pretty cheap at 87 cents a piece
drill (two drills is best, one to hold the drill bit and one to hold the screw driver bit)
scissors for cutting carpet
hot melt glue gun plus about 6-7 sticks of glue
wood screws (I used drywall screws which are just as good)
Some bits of metal to secure it to a cabinet at the top. I found some of those metal things that are used to block up the unused pci slots on a computer. They probably have a name, don't know it though.