I have this Plossl that can extend the eyecup 30mm. It isn't marked with focal length or branded, but it checks out at about 32mm and I seem to remember buying it from Gary Hand 20 years ago (not sure though).
The eyecup unscrews to give access to 42mm male threads.
I have no use for it. It needs a new home. So pay boxing and shipping costs and it is yours.
I will also throw a T adapter in with it.
Buyer pays boxing and shipping - $19 (USA)
I accept PayPal, Venmo, Zelle.