I agree with post #2, see if the clamp pieces (bottom left of your photo) can be flipped around, to fit various thickness of wires.
See if you can loop the wire around a screw or pin.
For looks it's hard to beat the molded strain relief on a commercial manufacture. It grips the wire firmly. When I make a repair I usually reach for hot-melt glue. I heat a stick over a candle, and daub it on or shape it with a small tool. However it's extremely sticky. You might have trouble if you want to disassemble the shell someday. Therefore stick a layer of plastic, etc., to the shell where you plan to apply glue.
An old-timer showed me how to make a mid-cable strain relief. Gather a half-loop, then wrap a rubber band around it several times. The rubber band gives when the wire is yanked. This takes strain off the connectors.