This was an ugly gray office chair we had around that had a broken pneumatic shaft. (I took the first picture after taking one arm off.) My cat really loves this chair and we haven't yet bought her a cat tree, so I thought it would be great if I could transform this into something resembling one. I decided on a two-tiered cat tree with a scratching post in the middle, a few dangly toys and a covered habitat underneath.
First I took everything apart to see what I had to work with, which was:
1 pneumatic shaft
1 5-arm caster base
1 L-shaped steel bracket
18 1/4" x 1" machine bolts
1 cardboard tube covered in sisal rope
1 bolt + washer
a piece of carpet on plywood
new fabric ($4)
4 1/4" x 1.5" machine bolts ($2)
11 #6 x 5/8" metal phillips screws ($1)
1 1.125" x 48" wooden dowel rod ($3.50)
2 tie plates ($0.75)
Step 1: Make It Pretty
First, the fabric. I covered the cushions and stapled with a staple gun. No need to be perfect. (Choose a prettier fabric than I did. I've since updated to something a lot cuter.)
Step 2: Attach the Scratching Post
I flipped the bottom cushion over and used a 1/4" drill bit to drill a hole in the plywood bottom and up through the padding of the base cushion; I attached the scratching post tube through the center of the cushion with its own bolt and washer. If your chair is all plastic and not plywood I think you should still be able to drill through it without problems.
Step 3: Attach the "Feet"
I flipped the chair arms over and reattached them to the bottom of the seat cushion facing the floor. This gave me a rocking base (great stool!). I flipped the L bracket over and reattached it using the 1/4" x 1.5" machine bolts. I cut the dowel rod into two legs each 11.5" long and screwed them onto the tie plates, which I then screwed into the plywood bottom to give a firm, stable base to the tree. Again, if your chair is all plastic I don't think you should have any problems with the drilling and arm attachments, but don't hold me to it.
Edit: I found in the end that the dowel rod legs didn't improve stability by any great degree and they were kind of flimsy in the way they were attached so they've since been removed. If you have flat chair arms you shouldn't have to worry about it, but if they are slightly curved as mine were, your cat tree WILL tip over if your cat jumps on the wrong spot or dives at it like a maniac. For future projects I would recommend either a thicker dowel rod so the screws don't fall out or a different attachment than a tie plate.
Step 4: Attach the Top Tier
I used a 3/16" drill bit to drill new holes in the plywood of the top-level cushion and secured the pneumatic shaft to its back with its own bolts.
The scratching post is actually a hollow cardboard tube, so I simply placed the pneumatic shaft inside the tube and secured the rim of the tube with epoxy. Be liberal with the application of the epoxy, especially if you have fat or boisterous cats like I do. The lift handle was difficult to remove, so I used it as a hanger for her favorite toy, Quadropus.
Step 5: Add a Hideaway Skirt
Use the extra fabric to staple a skirt to the perimeter of the base to make a hideaway. Original construction had the skirt wrapped around and attached to the dowel rods for closure and privacy as in the photo, but my cats don't care as much as I thought they might.
Ta da! Watch your cat enjoy the fruits of your labor.
Begin: 5/31/08 8:00pm
End: 6/1/08 9:00pm
Total cost: about $10
Total time: about 5 hours not counting trips to Walmart and Home Depot