Star Trek Cat Tree (with Enterprise and Romulan Bird of Prey)

I have a 2 year old cat Saavik who has tons of energy and likes to be up high. I knew I wanted a cat tree, but I think most cat trees are really ugly. I wanted something both humans and cats would enjoy, if it was going to stay in my living room for the foreseeable future. My solution was to build a Star Trek cat tree since my husband and I are big fans. 

Step 1: Materials

9' & 5' pvc pipe >> for trunks & ships
2' x 3' plywood board >> for base
15" & 18" pine round panels >> for saucers
1' x 3' plywood board >> for Bird of Prey wings
8 round caps >> for nacelle tips
4 flat caps >> for attaching the pipe trunks to the ships, and trunks to the base
3 T-connectors >> for the Enterprise
1 X-connector >> for the Enterprise
2 elbow connectors >> for the Enterprise
2 straight connectors >> for connecting the pipe trunks to the flat caps
15 2" length bolts (5/16" or 1/4") >> these are for attaching pipes to wooden boards
3 (2 1/2" length bolts) >> needs to go through both wooden parts of the Bird of Prey
18 nuts (same diameter as bolts)
carpet (I recommend getting "remnant carpet" which is ~50% off. We got 12'x4' and had plenty left over)
250 ft sisal rope (1/4" diameter)
pipe adhesive (smallest container available)

Tools:
utility knife (to cut the carpet)
handsaw (get a small one with a wooden handle that can cut pipe & wood)
staple gun (5/16" minimum length staples)
drill (to drill holes for bolts & put bolts in)
ratchet wrench (to secure nuts)
scissors (to trim the carpet)

Total cost ~$150 (we already owned a drill & wrench, plus we had a 10% coupon at Lowes)

Step 2: Enterprise

I don't have pictures of this in progress, because I didn't think of writing up my procedure until after we had built it. I've drawn a schematic of how it was constructed.

We attached the flat cap to the saucer section first, then constructed the rest of the Enterprise frame from pipe and pipe connectors. The pipes and connectors were glued together using the pipe adhesive. We carpeted the saucer section and the rest of the frame separately, then glued the cap to the T-connect using a small piece of pipe between them (not pictured in the schematic because I forgot to include it). I used lots of staples when carpeting, but made sure afterwards that there weren't any loose staples leaving pointy bits. Also, I put cardboard under the carpet as I cut it, to protect our floor and to contain the mess cutting and trimming carpet leaves.

Step 3: Romulan Bird of Prey

I have pictures of this in progress, since we did it second. We cut the 1'x3' board to the shape of wings we wanted. The little piece of wood was left over from cutting the wings & we used it to add more detail to the ship. We bolted the nacelle pipes to the wings, bolted the flat cap to the bottom of the center of the ship and glued the little piece of wood on. We carpeted the Bird of Prey after it had been entirely assembled.

Step 4: Platform and Trunks

We cut our pipes so that we had a one that was 3' and one that was 5' tall. After carpeting the 3'x4'board, we bolted two more flat caps to where we wanted the trunks, using 4 bolts per cap. We glued the straight connectors to the pipes, but we did not glue the pipes into the caps (this way the pipes can be removed if we need to disassemble the tree for moving). Once the pipes were in the connectors, we put the ships on the top (again, not gluing them in for future removal if necessary). Once the ships were on, I wrapped sisal rope tightly around the trunks to create scratching surfaces. I also stapled a bit of leftover rope to the bottom of the Enterprise as a toy.

Step 5: Final Concerns

As expected from relatively heavy objects on top of poles, our initial designs wobbled quite a bit. To solve this, we used L-shaped braces to attach the ships directly to the wall. This is optional, and there are other ways to stabilize it, but this is what worked for us.

Materials: 
10" L-brace
8" L-brace
1/4" screws (2-2 1/2" long)