I start with a scrap piece of wood, drawing a scaled down sketch of the shape. This helped me to determine the right proportions where our cat can play in/on it while the ratios look attractive as well.

The winning shape is chosen from my sketches and I scale it up and transfer it onto a piece of plywood. I use a piece of 3/8″ thick plywood for this since it is just going to be the frame and will have another skin of finished wood attached onto it. I use my squares to draw all of the straight lines and a string with a pencil on the end as a quick and dirty compass for the larger curves.

With one of the S’s draw out, I use my circular saw to cut out all of the straight lines and my jig saw to cut the curves.

I sand the edges smooth with my belt sander and then use the first “S” as a template for another one. They are temporarily tacked together with some brad nails and a pattern bit is used in the router to cut the 2nd “S” to shape

The two S’s are first held apart along the straight edges of them. I cut pieces at 12″ wide and the length of the straight edges and then cut dados in them so they fit over the edge of the other plywood. You can just see the groove at the bottom of the panel here, it has a little bit of overhang for the carpet that you will see later. These are attached in place with blue and brad nails.

Now to go around the curves, I just get some pieces of scrap pine that are about 2″ wide and install those in place with glue and staples in the end. I want to install carpet on the interior still, so I leave off a few of these pieces on the back side to allow me to still access the inside.

The inside carpet layer goes on first. I have an old stained carpet that the cats will love, so I first cut it down to the correct width and then spray the back of it and the support pieces inside the S with spray adhesive. Once that is tacky, I can put the carpet in place and I tack it along the edges with brads to help hold it in place.

With the carpet all laid down on the inside, I install the rest of the pieces of of wood in place and then proceed to the exterior surface of the S. I do the same with the carpet on the outside (this is all done in ~4′ strips). This time though, I cut the width of the carpet so it overhangs each side by an inch so I can roll it over later.

The installation of the pallet wood paneling comes next! (my cat love pallet wood). Each of the pieces has to be custom marked and cut to around the profile, but I hold the pieces at a 45 degree angle and start at one end. The extra carpet on the edges is doubled over and tucked in on the ends with each piece that I install. They pallet slats are simply installed with glue and brad nails.

Then it’s just a matter of working my way around the S shape with the pallet slats. This includes: marking the pieces, cutting them to size, applying glue and rolling the carpet edge over, rolling the carpet edge over after it pops up, carpet why aren’t you cooperating?!, and then brad nailing the pieces in place. And then I do the same thing on the back side…

Now to get the kitty access to the inside of the S, I mark out a circle at each level with my compass and then cut them out with a jig saw.

I cut 2 holes out at first, but decided to cut one out of the center later as well. The outside surface is all sanded smooth and the corners of all of the openings are rounded over to take away all of the sharp edges.

For finish, I apply linseed oil to the outside of the front and back to darken and protect the wood. Once the finish dries I can bring it up into the house so the kitty can likely sniff it once and never look at it again.