Summary

I needed an 8mm Cable joint enclosure. So I designed this one to fit my need.

Join the wires and pour in suitable resin and hardener. You could wrap the ends to make sure a low viscosity resin doesn't leak out the ends before getting hard. Wait to get suitably hard before burying or using as a waterproof joint.

You could change the % ratio to resize it to suite your need from the 8mm that this design uses.