I have a large collection of houseplants, and most do fine with standard pot I designed. However, I have a fair number of plants that need consistent moisture, like African Violets, episcias, terrarium culture begonias, etc.  You know, the ones that crisp up and die like the little drama queens they are when the moisture level isn't perfect every second of every day?  (I'm looking at you calathea!)   There are a lot of nice self-watering pots here on printables, and I've tried a lot of them, but most didn't scale well to what I needed, or they didn't fit with my aesthetic so I decided to make my own.

The pot insert DOES need support.  I tried and tried, but I couldn't figure out a way to design it so it wouldn't need support.  That said, I found printing it with the bottom on the plate and tree supports to use the least amount of material.

I print these in ABS personally, but ASA or PETG would be great too.  I wouldn't use PLA if you plan to use them for a long time. 

An 11-inch (28 cm-ish) long,  ¼-inch diameter (6 mm) cotton rope through the two larger drain holes is the perfect length to just barely touch the bottom of the reservoir.  If you scale the pot size, be sure to scale the rope length an equal amount.