For horticultural crops in my profoundly modest garden I use a nested bucket design. Two generic plastic 5 gallon buckets, like you would get at the hardware store nested. The top bucket has its base perforated with numerous 3/8 inch holes, one large hole-saw to hold a soil foot, and painted white to control solar heating and UV damage. I do not remember where I got the design, but the basic design is written up elsewhere now.
In last five years Albuquerque has gotten mosquitoes. Sigh. To deprive them of breeding grounds in my yard I made too modifications to the design. First, I don’t put in a vertical pipe that extends down to the water reservoir. Second, I use screen on the weep hole. The method for that weep hole modification is to use a multi-part 3D-printed grommet to mount in a drilled bucket. Here it is after a season of use, dirty but totally functional.
What’s shown is printed in black PET-G then spray painted white along with the rest of the bucket. The grommet, designed in FreeCAD, uses a threaded “bolt” with a saddle-cupped head to conform to the bucket contour. The other side of the “bolt” has a complementary curved washer and nut. The inside of the bolt holds the screen, retained by a threaded compression plunger.
The “bolt” is blue and clearly shows the conformal curve. The washer for the inside of the bucket is gray–it uses a D-hole to key its orientation. The nut is red, and the screw-in screen retainer is brown. The slot on the top of the plunger accepts a large flat-blade screwdriver.
I just ceased my container garden for the year. Three of my containers contained very little water in their reservoirs, though the plants were large and healthy. The system worked completely fine, as it has for years preceding the no-mosquito improvements. I will manually water buckets periodically next summer.