This 3D printed lid will automatically water your herb garden or starting pots. It will fit on a standard mason jar (two sizes, wide mouth and small mouth). A small mouth jar fits nicely in a standard size planting tray with 4 inch pots (pictured). It maintains a small amount of water in the bottom of the tray to keep all the pots watered. The plants in these pictures were grown this way. Pictured are basil, cilantro, spinach and arugula. Good for starting plants or cut-and-come-again lettuce and herbs. In the download files you will find .x3g files ready for printing. Also .stl files and the .blend files if you want to see the design in Blender. There are two sizes so you will find two of each file.
4 inch Square Pots: http://amzn.to/2oJfLiH
Planting Trays: http://amzn.to/2pkT5TV
Grow Light: http://amzn.to/2pCcIq3
Works at 15% infill. 100% might be more durable. I used ABS and sealed the print by brushing some acetone over it. This is not really necessary but in water, prints can be a little porous.