Seat is done!
I made a pattern on the foam using newspaper. I then transferred the pattern to some leather-like fabric I had left over from my Halloween costume, adding all of the seam allowances. I laid these pieces out on the pieces of leather that I had.
I actually sewed up a test cover using the fabric first to see how it was going to go. I was pretty happy with it so I started cutting the actual leather. Due to the sizes of the pieces of leather I got from my jacket, I had to make the top of the seat out of two pieces. I sewed that seam and them made the lines for the pleats. Cutout the headliner foam and sewed some lines.
Then I used my pattern to mark the edges of the top piece. I sewed all around the edge then cut it out.
Then I traced the pattern for the sides and cut those pieces out.
Finally I sewed all the pieces together and then sewed the flaps of the seams to make the french seams. The top piece ended up being too short partly because the pleating made it effectively smaller, and I had cut it a little short due to some imperfections in the leather. So I had to add another small piece on the front.
Miraculously, it fit on the seat extremely well. However, when I put it on the bike, it looked too thick to me. It was a total of 3 inches thick, which due to the size of the seat, seemed out of proportion. So I took the top layer of foam off (was 1.5") and put two layers of 1/2" foam on it. That seemed to be all it needed.
Next up was to install the cover on the pan.
I got the cover positioned correctly and then started installing the rivets. I used a drill bit to hand "drill" the holes in the leather as I pulled it tight. I actually started where the seat bends up at the back and then put the rivets in the ends, pulling everything tight.
I worked my way around the seat, pulling everything tight.
I trimmed the excess leather off of the bottom and installed it on the bike.
Success!
The leather is actually fairly dark, but the camera flash makes it look lighter in these pics.
I still need to glue down the leather on the bottom and then repaint the bottom black, but it is basically done.
Finally, ready to ride.