Yes, but there is a similar project in Hungarian forum, I do not know the status of this topic, may be Zozosoft can answer it.
I found Hungarian company which is few years ago produced keyboard membranes for Sinclair and Enterprise machines.
Now about 20 semi-finished EP membranes exist. For finishing them needed purchasing some materials.
The estimated price is a 8-11 GBP/membranes (+shipping). But the final price will be calculated when the project is finished.
The project will be started after the summer holidays.
Now we have Hungarian buyers for about 15 membranes.
But least one reserved for you, Tricky!