Flower watering ball (bulb?) / Bewässerungskugel für Blumen

Update 31.05.2019:

This thing now has a big sister. You can find it here:
https://www.thingiverse.com/thing:3665139

Update 30.07.2018:

I recently tinkered around with the settings and learned the following:
-you can print this airtight with 0.2 mm layer height with the extrusion multiplier set to 150%
-when printing in 0,1mm layer height the extrusion multiplier just needs to be increased to 130%
-when setting up the post processing for the speed change choose 'change speed' and not