We bought a PVC tube of 75mm-diameter to test the material in which we'll build the ultimate structure. We drilled some holes of the size of cups and we put in some cuttings we had prepared before, with roots already grown. We bought a light and a timer to simulate daylight.
We built the second prototype to create a water sheet at the bottom of the tube (horizontally speaking). We left no slope this time. Apparently, It had a leak, which we fixed, probably. In any case, we'll see tomorrow the consequences.
We'll keep you updated! ;)