I've been trawling through the searchs thingy but I'm not having much success!
The distance between my transmission tunnel and the inside if the side (!) of the car is 15". I have started to make some seats out of tube and they just need the webbing/springs/foam/etc.... but I was wondering what other (locost/cheapo)options I have? I'm happy to attach pads to the inside of the car for lateral support (there's not much room for movement with my fat ar5e).
Any help will be appreciated.

After months of screwing around and getting fed up of being too poor to be able to drop $500 cnd on seats I have got my bench seats figured out. just alot of experimenting to get the foam shaped right- even have some lumbar suport.
If things work out I should be sewing tommorow. Being covered in black and white marine vinyle.
Dale

I cobbled together a couple of seats here....



These are a nice fit but with the best will in the world, will always look cr4p!

I had grief finding seats to fit my pre-lit westy as it was very restrictive space wise.
Ended up going with intertrim rangers, fit fine and where suprising comfy

I have had a good old tidy in the garage and found the plastic 'school' seats that I nabbed to go in the car. They will do for now!!

I've got a pair from a Bedford Midi van, they're narrow enough. Even if I don't use the foam the frames'll be a good starting point. Also same seats in Bedford Rascal, Suzuki Super Carry, Toyota Hiace.

Good plan! I'll have a ride to the scrappy on Tuesday.

I was following a Daihatsu hiJet pick up the other day and it had seats which looked like they might be a good shape for a locost you can see some in this van here. Don't know what width they are though.

Forgot to mention the Hijet, I think it was another product of the collaboration that produced the Rascal/Super Carry. You used to be able to purchase a kit from someone along the lines of NF Auto Developments to re-trim a pair of these seats but I don't know whom/whether it's still available.