durable good to print Z axis coupling 5 to 8mm Prusa Mendel

I'm new to the 3d Printing community, so plz feel free to comment, suggest, help me to improve.

Thoughts about it:

Should be durable,
round steppershaft should be able to be tightened quite tough,
should be easy to print
small z-axis adjustements should be possible

This item may look a bit similar to others here, but i ensure u i made it right from scratch, and if u're interested i can mention the details.