This is a watering spike for small pot plants. The idea was essentially copied from this design which the creator posted on Reddit. Thanks to the original designer for sharing an interesting concept. I wanted to make some changes, so I created a version in OpenSCAD.

There's an inner spiral to give strength to the main column, so the outer walls can be thin - the one shown in the picture has 0.5mm walls so it's quite economical to print. It functions to allow direct watering to the bottom of the plant - there's no bottle attachment - see other designs for that, or modify as you choose.

I printed in PETG but it would work in PLA. No special printing considerations. Print in the original orientation of the .stl or .scad.

To use the SCAD you'll need to install the BOSL2 library. It's quite simple - see the notes in the SCAD.

The included .stl should suit most small pots - it's about 90mm total length.

Note: I wouldn't scale this to make it much larger. If you need a watering spike for larger pots or outside tubs then it's probably easier to buy some plastic water/waste pipe from the hardware store and drill some holes in the bottom and possibly use a funnel for filling.

Verdict - I'm still undecided about how effective this is. That's more a comment on watering spikes in general. They're more convenient than regular bottom watering, but maybe not as effective. I'll leave you to make up your own mind.