My Bucket seats are Cobra Monaco S but this technique could be applied to most steel construction seats (even standard seats). A similar technique could be used with 'proper' composite seats too..
First up was to snip the hog rings (copper colour loops) around the base and 'peal' the seat.....

Inner of seat now revealed and the base foam was especially goosed. Also the back foam was deemed 'tired' so striped out....

New foam kit was made up....i have 'upgraded' seat base from 1 1/2" to 2" foam as it gives a little more comfort. Back foam was a like for like 1" replacement, and 1/2" everywhere else....

All glued in and looking good as new....(front lip area not installed in pic though for some reason?)

Now roll fabric down and refit to rails underneath using hog ring pliers and hog rings. This may differ from brand to brand or composite seats may be glued in or even elasticated around the base, but the foam ellement will be the same. And before anyone gets too excited, the foam is all fire retardent and meets regs....its just a different colour as different densities of foam are different colours...blue is firm.
Hog ring pliers and ring placement....



Finished pic's to come later when the interior is reinstalled and looking more presentable. Hope this has helped....get on fleabay and buy some bargain second hand seats and refurb some yourself