You have a few options when it comes time to figure out what you're going to use for a seat in your hot rod project. You can try to resurrect your original seat (if you still have it). You can scrounge the wrecking yards looking for something close and then modify it to fit your particular ride. You can buy a nice new seat from one of the companies advertising here in R&C. Or, if you have a hot rod that might not be able to use an off-the-shelf seat and you like to do things your own way, you can build it from scratch. That's what I did.
I chopped the top of my '32 Ford pickup 4 1/2 inches and channeled it 6 inches, which left me with almost no headroom and very little legroom. What I needed was a seat that was extremely low and compact, but I wanted it to be comfortable too. I also wanted to make the seat with kind of a traditional look so it would match the style of the rest of the truck. So I set out to make a bench seat from scratch using modern "no-sag" springs for a soft, smooth ride, and shape the seat and springs to cradle me in comfort.
I experimented with scraps...
I experimented with scraps of plywood and firm foam to figure out the most comfortable shape of seat and the slope of the backrest and then used 75x.75x.125-inch-wall square tubing to make four support feet and the perimeter of the seat frame.
I figured on using about 2 to 3 inches of foam, since good-quality foam rubber compresses about 50 percent when you sit on it, so I designed the springs to be about 1 1/2 inches lower than where I want to be when I sit at ride height. I also took into consideration the fact that the no-sag springs would flex down with my weight on them, so that put the bottom dip of the seat springs only inches off the floor. Luckily, I built the floor with a recessed area right under the seat so I'd have a little extra space before bottoming out.
The cramped interior in this truck forced my knees up high so I needed much more thigh support than I would in a car with lots of legroom. It turns out you also need more support rolling up the back of your tailbone when your knees are up high, otherwise it feels like you're sitting on a hard, flat floor. So what I needed was a deep bucket-shaped bench seat. The foam can be contoured to fine tune the shape of the seat later, but getting the support structure shaped to fit comfortably seemed to be the best way to wind up with a comfortable seat. If I can make it comfortable to sit on without foam or upholstery, then I know it will really be comfortable when it's all done.
 I chopped up some lighter...  I chopped up some lighter .065-inch-wall, .75x.75-inch tubing to make the seat back. This angle clamp made it easy to weld the mitered corners at the top of the seat back. |  I butt welded the seat back...  I butt welded the seat back frame to the tops of the rear sides of the base. Diagonal braces will be added next to give it more support. |  Before going too far, I piled...  Before going too far, I piled 1 1/2-inch-thick wood slats onto the dipped seat frame to simulate 3 inches of foam after compressing and then had my son Max check the seating position and comfort so far. |
 Once I was sure what slope...  Once I was sure what slope I wanted for the seat back, I welded in the lower horizontal tube for it. The lower horizontal tube needed to be spaced up high enough to allow for the built-up layers of foam that will make up the bottom cushion. |  The nine-gauge no-sag spring...  The nine-gauge no-sag spring material comes off the roll pre-curved. A 110ft roll of it cost me $30. I used these tools by C.S. Osborne & Co. to reshape the springs as necessary. |  I used 5/16-inch-diameter...  I used 5/16-inch-diameter cold-rolled steel rod bent on a Harbor Freight bender to define the curved corners and the overhang at the front edge of the seat. |
 I used more 5/16-inch cold-rolled...  I used more 5/16-inch cold-rolled steel rod to define the shape of the seat back along the top and corners, tapering it gradually at the lower ends. |  After seeing a picture of...  After seeing a picture of a professional "spring kinker" tool, I made this tool myself out of some scraps of bar stock and a grooved aluminum disc. |  |
 I straightened out the first...  I straightened out the first four loops of each spring so they would have the contour I wanted when they were pulled to fit the seat opening. |  Thinner 11-gauge springs were...  Thinner 11-gauge springs were used for the back cushion and mounted the same way. I straightened out the top four loops of each back spring, which made the upper part flatter but left the lower part arched to give better lumbar support. |  I didn't like how the front...  I didn't like how the front lower edge of the seat looked so high off the floor, so I added more 5/16-inch rod to redefine the lower front corner of the seat. |
 I cut 5/16-inch od .050-inch-wall...  I cut 5/16-inch od .050-inch-wall steel tubing into a bunch of 7/8-inch-long pieces to make the spring anchors. |  Here's the seat with all the...  Here's the seat with all the springs installed and trial-fit back in the cab. It was actually nice and comfy, even with bare springs. |  After bead blasting the seat...  After bead blasting the seat and shooting it with two coats of Zero Rust flat black paint, the seat frame was done. Total cost: about $100 and three days of work. |
 The kinks in the ends of the...  The kinks in the ends of the springs keep them from sliding out of the anchor tubes, which were welded to the seat frame. I avoided blowing holes in the thin tubes by using short tack welds. | | |