If you can't buy what you want then make it, so i did, this look isn't everyone's cup of tea or whisky & cola but it's mine, the white Venetians just don't work for me at all & wanted some more wood grain in the car.
I use cedar Venetian blind slats (2nd hand) manufactured the mounts & brackets & opted not to go a full curve, the main purpose is to keep the hot Aussie sun of the back seat area, tested with a drive to the Nth Shore car show in Sydney & served it's purpose. I have taken note of what i did and the measurements which are for my xj6 S2, i haven't tested them on any other model but if anyone is interested in the info your welcome to it, might get your imagination going to design something that's your flavour....comments or questions welcome...thank you...tom

 

Something retractable might not be so bad. Im always up for diy reads tho.

Along those same lines, has anyone made a full window EXTERIOR setup like this as seen on, say, '70s firebirds etc?

Not my cup o' tea really but "vip" style curtains/blinds may have some interest as well.

 

Those, and ones on Datsun Zs, tended to part company with the car at some high speeds. Could be embarrassing in some situations.

My husband lost one once.
(';')

 

well one thing for sure, if my Venetians break loose it would mean the back window has come in or out due to unwanted forces so if the headrest doesn't stop it then i've got bigger problems that's for sure...tom