https://www.thingiverse.com/thing:3382756
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I liked the holder, but the curves were a bit too rough for me. So I redrawn it for a higher resolution. I also suspected a predetermined breaking point on the slope above the holder and rounded it.
I think it's very nice to insert it into the screws, but it doesn't make sense to me if you can still see the screws - then a simple hole would have been enough. So I covered it up.