A credit card would be the best tool you could use. I redid the seats in my 84 F150 and my 66 mustang. If not for the fact they were machine die cut, sewn, ribbed, and pocketed there is no chance they ended up looking decent. All I had to do was hog ring them and they still were the second biggest pain I ever did (first was wiring that SOB). I couldn't imagine trying to get the measurements, cut, sewn, and reinforced in the right way to make it not just all fall apart the second you sit on it.
Not trying to be a prick here because you have done other great work, but everyone needs that realist voice to remind you of options.