I had considered making some seat covers, as I need to do something with my seats anyway -- the foam and hair have long degraded. An option I'd considered is reproducing the seats from the Rallye, which resemble a certain Recaro model, through GTS Classics out in Texas. He has some 300SL fabrics as well as other Mercedes fabrics. There's one sample that has the same light blue of the body, cream of the wheel, cognac/brown of the MBtex elsewhere, and beige of the carpet. I think it could look snazzy, though a gal pal of mine says it could clash with any outfit I wear. Well, she doesn't get to vote!
From the catalog:
Upholstery in MB-TEX (in place of cloth): Washable and hard-wearing. A wide range of colours and patterns, fully or semi-piped. Available for saloons models of 190/190D, 220S/SE, 300SE, 300SE long and 230SL.
But after pulling out the 230SL brochure (covered in the first owner's pre-Excel tally of option combinations!) and reading closely the section about the interior, it appears nowhere is cloth mentioned -- only leather and vinyl. So no wonder one doesn't see cloth anywhere. It is odd to me that it evidently wasn't considered an option even though it appeared in the up-market 190 and 300.