The main reason why I made this project is because my cat loves to sleep by the radiator and look through the window, but the shelf we had was too narrow (see pictures in next step) and he could hardly keep balance on it (one day he fell from it because he fell asleep).

Step 1: Design

The initial idea was to build an extra shelf where he could sleep and not fall, but as I was working on the design I decided to make improvements:

- Wrap the extra bar with rope so he could use it as scratcher

- Leave a 2cm gap between the old shelf and the extra so that the warm air from the radiator could flow right to him

- Add a few hanging toys

The structure is formed by four L shaped flat corner brackets and a wood plank. Two of the brackets will be attached to the sides of the shelf and the other two (which will be holding the plank) will be united to them using two bolts and nuts. In the picture above you can see the forces in the system.

Step 2: Materials and Tools

4 L shaped flat corner brackets

2 bolts that will be cut to the right size and its nuts

4 short screws

25m rope

6x1.5x100 cm plank

Your cat's favourite toys

Step 3: Attaching the Plates

- Place the plate on the side of the shelf and mark with a pencil where to drill the holes for the screws. Make sure that the vertical part of the plate sticks out the shelf so that the other plate can be attached

- Using a small bit drill the four holes

- Attach the plates to the shelf

- Join the other two plates to them using the bolts and nuts. I couldn't find any bolt that fit the thickness needed, so I had to cut it to the right size

Step 4: Adding the Extra Plank

- Place the plank in its final position and mark with a pencil where the holes need to be drilled

- Drill the holes using a thin bit

- Attach the plank to the plate using four screws

Step 5: Make It Cozy and Fun

According to the calculations I made, I need 24m of 3mm thick rope.

- Wrap the plank using the rope. Take your time to do it very tight because cats are known to be massive destruction weapons and they will destroy your work with no mercy. You should also apply some glue. If you don't put glue on the plank the whole wrap will fail if the cats cut the rope.

- For the ends of the rope, tie a knot around the previous loop and hide the rest under the rope that wraps the plank. Use a small screwdriver to pass the end under the wrapping rope, as seen in the first picture.

- Tie the toys to the rope and hide the end of the rubber band under the rope

I also painted the radiator and the shelf with white paint.

Step 6: Let the Fun Begin

As you can see in the pictures, he uses the extra scratching plank to stand, sit and sleep. He loves the new scratcher more than the one we had so we got rid of the old one which was much bigger and occupied a lot of space. He gets crazy playing with the toys both when he's sitting or laying :D