I set some wire in the mold which will produce the holes for the plug wires to fit into.

Disaster on the first attempt. The rubber only reached half way before moving across and up the vent path. This means I have to make a modification to the mold.

The good news is, it does produce some nice seals.

The modification, a filler/runner that enters from the bottom, this should solve the problem.

The first half of the new mold under pressure, until fully cured.

How they look coming out of the new mold. I will now make resin copies to make multiple molds.

This is it removed from the mold. Using the correct diameter pins makes a big difference. :)

This is basically how you will receive them, with the pins in. Obviously remove them to insert the plug wire.