My design may or may not contain the same keys, because I am not sure how many would want the original APL character set.
APL keyboards are available, so the market exists , but that doesn't mean much. I plan to have the micro-controller user-configurable and replaceable, so one could change what symbols were type-able with the same keyboard. As I expect to use UTF-8, this keyboard could be used to type any character in the UTF-8 code pages.
 = https://en.wikipedia.org/wiki/APL_(codepage)
 = https://geekhack.org/index.php?action=dlattach;topic=69386.0...