I had some problems with the original (https://www.thingiverse.com/thing:2937504/remixes) breaking off at 7mm diameter.
So i made a vertical version.

I printed these laying flat, not standing, to get more strength. I printed with normal support only where touching the buildplate.
The result is quite ugly, because the support don't get off very good. But this doesn't matter its under the earth anyway.