I have spent a bit of time now learning how to use onShape.
It's a web browser based 3D modelling/CAD application.
The horizontal planters that I setup have been failing, primarily due to the fact that I cannot maintain a consistent environment for the lettuce I am using as the experimental crop.
Basically, the plants get too hot and whither and die. They like the sun, but not so much the heat.
So, I'm looking at passively cooling the plants using a 3D printed PETG planter pot. The idea behind this is to create a hollow ballast within the plant pot that I can use a cheap 3-6VDC submersible pump to circulate water through. This should in theory provide enough of a heat exchanging effect that the soil (which is where the plants roots are) should be kept cool enough to keep the lettuce from wilting.
I was able to get a great deal on about ten of the pumps on AliExpress for about $3 dollars a piece. Once I have them running non-stop I can determine their mean time before failure.
The idea is to create a hollow membrane with a nozzle at the top and bottom to allow the water to flow through it actively cooling or heating the soil up to a base temperature.
I will be adding a mount point for the two soil moisture sensors I am using as well as a wiring harness to connect those sensors to a base controller unit in the form of an esp8266 microcontroller.
I am pretty excited that this design will work, although I suspect I may need to tweak it a bit to get it working properly.
Here's a test video of the pumps I'm looking at using in action:
And here's a close-up of the pump and hose:
Here's a shot of the pump, hose and the soil moisture sensors connected to an Arduino in the background.