Edit: 03/10/19: Changelog v2.1: increased the distance in the socket to avoid collisions with the windblocker-holder and opened the gap a bit further. Pretty usable now I think.
Edit: 09/30/19: uploaded a v2 with a smaller size and removed the bag holder as it won't hold the weight of a grocery bag. Added a notch for mounting without breaking.
ATTENTION: I've not printed it yet and don't know whether it works. Feel free to try and give me feedback. :)
I discovered 2 13mm holes in the trunk/boot of my BMW Z4 E85 Facelift 2.5i and decided I want to have a James-Bond-Kingsman-Like Umbrella Holder where the Umbrella is in the trunk in a vertical holder.
On top I've added a possibility to hang a bag so it won't fall over while driving.
Anyway I don't have a 3D Printer so I have to wait until I can try if it works but if you want to help me to improve the product feel free to print & feedback. :)
Of course this should work with other cars as well in case they have such 13mm-diameter-holes. And I know that a wet umbrella will make my trunk wet but my little folding umbrella makes my stuff wet yet as well so at least no decline in this point. Couldn't afford a Rolls Royce so far. ;)