similar thing for the Commodore PET, the spacing was a little larger and there were no keywords to fit in, so I was able to fit the normal and shifted symbols in around each key.
membrane overlays for the ZX80/81 which stick over a ZX81 membrane keyboard, in various colours and BASIC versions. As there is no visible switch element, there is space for all the artwork, keywords, symbols etc.
Minstrel ZX80 clone page.
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