Micah Froese wrote:

Is there a source for the required latch and hardware or has everyone just
been putting something together themselves?

Micah,
I made two of them out of phenolic block and aluminum pins. Both are
actuated by reaching into the left air inlet on the front of the engine
cowl. On Jim White's airplane, the remote pull wire releases a
"conventional" tapered pin latch that allows the oil access door to hinge
open. On my airplane, the door pushes down slightly into the engine
compartment, and slides forward inside the cowl, leaving the opening
completely clear. When closed, air pressure from inside the cowl holds the
flanged access door tightly in the hole. I could send pictures of
either/both if you're interested.

Bob Pastusek