Apple 2e - building a simple expansion card and calling it from BASIC (or assembly)?

[mad.scientist.jr@gmail.com]

Has anyone built their own Apple 2 expansion card and programmed it to
do something?

If it wouldn't be ridiculously hard, I would like to try etching a
circuit board to plug into one of the expansion slots on my 2e. The
board would contain a single relay, which could be opened or closed
from BASIC code (or if it is not possible from BASIC, from 6502
assembly).

I'd also like to have the board contain 2 leads that the computer
could tell when they are connected together.

Maybe later I would expand the # of relays or leads, or build an
additional card or two, for more "inputs" and "outputs".

Any information would be appreciated...

Thanks