This is an old post, preserved for reference.
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Introducing another keyboard option for the Minstrel ZX80 Clone.
2022 Update: At the time of writing, there are still a few Minstrel 2 (ZX80) and Minstrel 3 (ZX81) kits available from The Future Was 8 bit Those have this type of keyboard built in. But be quite as those are the Final Edition kits, there are unlikely to be any more.