It's not realy my post. I was just brain storming yesterday. I look at the setup in the youtube video and I would prefer to invest in a pancake lens for the RF mount if I want it to double as a macro lens. I guess the only realistic solution is that ...
it's super niche, and noone will realistically make it, but it could have a use case for something like this https://www.youtube.com/watch?v=PW-44IKD8l0
Ofcause it is, but it will only wotk for macro. It will just be an extention tube where you can use a product like the Meike MK-C-UP, witch dont exist for the rf mount.
Someone odd to make one anyway. I know that you will not be able to use an rf lens on an ef body in a normal way, but in case that want to play with extention tubes for macro phortography it could be usefull to be able to mount en EF adapotor on an R...