The finished product:
After having a Mazda Miata I campaigned in autocross on the East Coast I knew I liked the feel of the seats.
I got a pair of seats in decent enough shape from the wrecker. I completely disassembled, sanded and painted the steel pans, and then fully reupholstered them with a decent vinyl kit from online. The next thing to do was to mount them.
The brackets are very different on the Miata seats, so a little modification is in order.
The first issue is the seat rails are longer and narrower than the stock sliders. This required a new mounting method obviously. I went round and round with ideas but settle on the "Keep It Simple Stupid" method of... a rectangle.
I measured and cut the angle stock to fit between the stock mounts and extending to the seat mount points.
It allows: full contact along the stock seat mount platforms, full support under the new seats, full slider range of motion, and it's fully reversible in the future for both the seats and the car.
I have it bolted for proof of concept but will get it welded in the future.
If I can do it, certainly anyone can do it.
Any type of metal cutter (I used a sawzall).
Or welder if you have it.
1" angle steel 1/8 thick. (could also use 1" square tubing but the seat sits higher)
Grade 8 bolts washers and locknuts.
Finally, I trimmed all the steel ends, painted the brackets and reinstalled. I'll also be covering them with upholstery vinyl for a more hidden look in the future.