The original window farms was a great Idea. Only the connectors between the bottles were a weak spot, and a rather heavy improvisation for my taste.
So, I redesigned this part for ease of use and being 3D printed.
If you want to know more, read my post on the windowfarm revived.
5 plastic bottles (change the number to your needs)
4 rubber bands (mine are 2mm wide - number of bottles minus one)
about 3 metres of strong cord, mine is about 2mm in diameter
dark spray paint
clay plant pellets
4 plants (number of bottles minus one)
4 hydroponics flower pots (number of bottles minus one) - if you can't get those, get black 'inside flowerpots'
27-30 mm crown drill
a drill roughly the same diameter as the cord.
Step 1: Get As Many Bottles As You Need; and Prepare Them
A windowfarm is optimised in columns of variable height. The smallest farm consists of one column, which may vary in the number of plant-bottles, and therefore in height. In my case, it's 4 plant-bottles plus the reservoir-bottle. This sums up to slightly less than one and a half metre.
Therefore, in my case, 5 bottles are needed.
Free the bottles of their wrappings, and wash away the remains of the glue.
Step 2: Tape the Bottles.
Since you want plants to live inside of the bottles, you should fit their home to their needs. The plants' leaves collect light, while the roots are sporting more of a Dracula-mode, in that thy don't like exposure to light.
So, because the bottles are going to be hanging upside down, you need to tape the lower part of all 4 plant-bottles in a way that will keep spraypaint from sticking there. For the reservoir-bottle you just need one strip of tape. This is because you'll want to see the amount of water inside, but discourage algae from living here. Algae would just clog things. Which is something you don't want it to do.
Step 3: Spray-paint the Bottles
After taping the 5 bottles, spray-paint them in a dark color. I chose a grey which was at hand. But you can basically use whatever you like or have lying around. The less light gets through, the better.
Step 4: Print Connectors and Make Gasket
Download the connector file on Thingiverse.
Print it once for every plant-bottle. In my case, that's 4 connectors.
Get a rubber band placed inside one, mark the intersection point with a sharpie, and cut once on the line, and once about 5mm beyond. This produces a small overlap, which ensures the tightness.
I don't recommend making significantly larger overlaps since in my experience this had the opposite effect.
After cutting the gaskets, place them inside the connectors, and screw the connectors on the plant-bottles.
Step 5: Draw & Cut Circles
After screwing the gaskets onto the plant bottles lay the bottles flat on the table and let gravity position them with the 'trunk' facing downwards.
Draw a sufficiently big circle on the top side. You can use my template for this.
Cut the circle from the plant bottles.
For the reservoir bottle, a small hole near the bottom of the bottle is necessary for air flow. Since I plan to apply a pump, I used the oval in the middle of the template, so I can put a hose in there.
Step 6: Drill Holes Into the Bottles
Get one of those wide drill bits shown here, with a diameter between 27 and 30 mm.
With this, to drill a hole in the bottom of all bottles, then use the printed part to connect with the next bottle.
Now you should have a row of all plant-bottles and the reservoir-bottle.
All the printed-parts-'trunks' should face away from the holes you cut earlier. If you missed this, the water coming from here might spill to the floor. In this case, you can either cut a new bottle, If you have one handy, or print the flipped version of the Thingiverse file.
Step 7: Thread the Cord.
Now, position your row of bottles in such a way that the reservoir bottle is lowest, and all the bottles are upside down. This is just the way they'll remain.
Now we'll apply the thread. Depending on the fit of the bottles in the holes, and the quality of the printed parts, it might work without the thread, but I don't recommend doing this and don't take any responsibility if you try this.
Start threading the cord through the lowest small hole of the reservoir bottle, then out the next, and again in & out. Repeat for all the plant bottles on this side. Leave some cord atop the upper plant bottle for later fixation, and work your way down the other side. This is fiddly work, I know. But it's an easy way to get these bottles to hold on to one another.
Cut the cord, make knots into the ends, preferably 8-knots like shown in the picture. Then cut the ends. I left some loose for possible later adjustment.
Last thing is to take your pliers and rid the cord of any slack.
Step 8: Prepare & Insert the Plant Pots.
I recommended getting hydroponic flower pots. I couldn't get those, so I got the black inside ones and drilled some additional holes into them for water flow.
Fit them into the bottles. if necessary, fit them in with your scissors.
Step 9: Plant Your Plants.
Get every flower pot about 3/4 filled with clay pellets. Free the plants of most soil, then place them inside the pellets.
Take one last check if everything's right, especially that the reservoir bottle is closed with a regular bottle lid! Then pour some water into the top bottle and watch it dribble down to the reservoir bottle.
That's it! You're finished!