Can anyone make custom controller converters?

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Constructing one adaptor like that from scratch would be quite difficult, as it involves some non-basic electronic skills. It would be much easier modding the current existant converter. However, I'm not sure how is it designed, I understand that changing the lay-out of the 4 main buttons would be very easy, but being able to use the R1,R2,L1 and L2 buttons as you want could be more difficult.

are the 4 of those buttons activated by ground or are they activated by a juiced common?

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