Ah. A lesson from somebody who's built hardware that I'm sure you've now learned: make sure connectors can't plug into eachother unless they're supposed to. Even if they're different connectors, different keying, whatever, sometimes they can still be forced together.

I've seen datacenter techs successfully force an SFP optic in an RJ45 port. So yeah, the shape needs to be very different.

This is good advice for robust design, but I swear, 9 times out of 10, you will be the one who keys it the wrong way during CAD layout.

I built a lot of Ikea last month. And I was just marveling how cleverly designed everything was so that it was quite difficult to put two wrong pieces together. Mostly, the only warnings in the manuals were to rotate a piece correctly.