Re: How to upholster these roto molded seats?
Covering chairs is a bit of an art, I have seen it done but never attempted it, I am pretty sure you can't just buy a piece of vinyl and glue it to the chair and have it look even close to presentable, pretty sure there would be some(alot) sewing involved.
If you have the money check around for an upholstery shop in your area, you may be suprised.
If you want to try it I would think you could glue the foam to the frame but you would have to staple the vinyl over that, as I said , it is a bit of an art to get it to look good.
Good luck.