I tried doing this about a month ago to cover up a severely faded sunbird turbo tach. I found a few designs here on the forums and ended up doing a few more myself in photoshop, but none of them lined up with the original gauge face design (looked good during the day, but didn't light up worth a crap at night). I ended up scanning my gauge face and color correcting it using photoshop and paint, but couldn't quite get it to line up with the original guage, so I scrapped the project and came up with another solution.
The mazda guys are unique in that their gauge faces aren't printed on the clear plastic that distributes the light evenly. They just remove the factory overlay and install their custom ones, so there's no fuss with trying to get the two lined up correctly so that light can pass through properly.
'87 GT 3.4 pushrod daily driver
'88 GT 3.4 DOHC swap in progress