This was a fantastic model, thanks for sharing it! Printed three modules, reservoir, funnel, and cap on an IC3D Mendel Max using green 3mm PLA filament with 20% infill for everything. The prints took about 12 hours per module (three), with the reservoir, funnel, and cap taking around 4 hours or so each.
The only modification I had to make was flipping the funnel so that it printed with the wide side down. For some reason the default position was to print from the narrow part first (which wouldn't be stable without support, so I flipped it and all was well).
I also had to fiddle around with where to drill the holes, and what size they should be. If I had to drill the reservoir again, though, I'd probably drill more smaller holes rather than the 6 larger ones around the perimeter. Maybe I should print another one... since this is an incredibly modular system, it's trivial to pull apart and swap things out (or expand!) whenever you want.
Now... onto planting!