I had tried several other plant watering spikes but they all broke if you tightened them too much so I designed my own.

I got stuck when I found out that standard bottles don't use either a standard or metric thread type, instead they have their own standard.

If it wasn't for https://www.thingiverse.com/thing:2693686 PCO1881 (Soda Bottle) Thread profile for Fusion360 by terahurts December 06, 2017 this wouldn't have been possible so major thanks to them.