Thought about wire connectors

I’ve been trimming male and female headers in order to create connectors for stepper motors.

This seems to work great.  I tie a loose knot in the wire to prevent them from pulling apart.

I noticed the female connectors are often easy to pull out. The little metal clips can pull right out the back if you apply a bit of force. Especially after the soldering as I’m sure the heat might damage the plastic parts.

Any suggestions on how to keep the wires from pulling out the back?

Wrapping with electrical tape looks bad and it may not work well. I thought of making some sort of clip on a makerbot. It could crimp onto the wires and also be a friction fit to the connectors. But that’s lots of work and I wanted to see if there was a better solution before getting busy with that.