I bought Spank Lock-on grips (https://spank-ind.com/products/spoon-grips), but they came with just one lock-on and an alloy end cap. I needed two lock's because I have bar-ends.

I designed this part as a replacement. It uses a M3x14 screw, while the original uses M4 threads. It seems to work fine.There were printed in PLA, I don't know if they will be durable enough, PETG or ABS would be stronger...

I've included the openSCAD file, but this one contains some hardcoded measurements.