This is an Ikea hack so that my cat Lama can go out my window on the 3rd floor and get down from the roof via this cat tree. I haven't tried my hand at too much building, so it was great that I was able to knock this project out in a few hours of shopping and constructing. If you have more skillful ways with lumber, or a lot of scrap materials lying around, then by all means, use them! It'll cost you a lot less.
Step 1: Materials
I used a couple different sizes of hose clamps, screws, phillips and flathead screwdrivers, a power-drill, a staple gun and staples.
Step 2: Hose Clamp the Shelving Brackets
Figure out where on the tree you want your first platform to be. Mine was about four feet off the ground.
Hose clamps are really easy to use. Loop them around the tree and through your shelving brackets. Tighten them up real good with a flat head screwdriver, adjusting the position as you go to make sure that the platform will end up where you want it and that the brackets will give even, level support to your shelving platforms.
Step 3: Screw the Platforms to the Shelving Brackets
Lay your platform on the shelving brackets, making sure that everything is snug, and use screws to secure the platforms to the brackets. On the first shelf I just used a screwdriver and went up through the pre-drilled holes in the shelving brackets, but the screws were too long and so I ended up having to cut them off. I used a power drill for the rest of my platforms and screwed down from the top.
Step 4: Staple the Carpeting to the Platforms
I didn't bother to trim the carpeting squares, they were thin enough to easily wrap around and staple to the underside of the platforms.
Step 5: Repeat Steps 1- 4 for Each Platform
By the third platform I'd run out of small hose clamps, so I wedged a spare cut piece of tree limb into the hose clamps. Hopefully you'll have a ladder handy for this project. I didn't and ended up climbing this little tree about 6 or 7 times.
Step 6: Optional Window Platform
I also added a platform outside my 3rd floor window to make it easier for the cat to go in and out.
Step 7: Try to Get Your Stubborn, Suspicious Cat to Use It
There was a can of tuna fish involved the first time. But now Lama goes out the window and down the tree quite happily every morning.