3D printing is the way. I have no clue how to design anything in CAD but as Steve said lots of people are enthusiasts so should be doable.
To me, it looks like an easy metal lathe project. Get a piece of round stock, bore it, shape the nice curve on the outside, and part it off. Probably make a handful while you are tooled up. Not sure what material would be best but 10 minutes on Google would probably solve that question.
In other words, if you walked into a machine shop with your piece of round stock from Amazon and your broken original, it would be $X for 1, and probably $X + $5 for 10 of them.
Dan and Bethany Moore
Blue Phoenix - 2008 Selene 59-17