I live in London, I love chillis, I love to grow chilli's ... but we haven't got the space.

I've always loved chilli's, my passion quickly moved me to creating them myself. For about 3 years I successfully grew, harvested and feasted on them, creating offsprings  and sauces which I gave to friends. All of which happened on the windowsills of our one bedroom flat in Ealing, London. Unfortunately the expansion of my hobby didn't fit very well with the house (or my girlfriend). The plants loved it, a south/west facing corner of the block ... but they didn't look very good and they shed a lot.This is a picture of the early stages.
I've always been fascinated by bonsai plants and was under the misconception (as a lot of people are) that they are specific "mini plant" genus. I bought the default chinese elm starter plant and got stuck into some research. Obviously my misconception was quashed as I delved further into the bonsai world. My ureka moment was when I found the bonchis (bonsai chillis) guide on fatalliis website. Here's a specimen from his amazing collection.
... a great opener into my chillibonsai experience.
So, I miniaturised all of my chilli plants and they are loving it thus far.  They quite like it and have been growing well for about 5 years now.
Last year I decided to try to use an automatic watering system I purchased from willowbog and by the time I came back they had only just survived because the house was not as dry as I had anticipated and they were overwatered.
The watering system didn’t fail, it worked as it should by pumping a specific dose to the plants every 12 or 24 hours whether they needed it or not. Obviously this is not very good for bonsai … you might get away with 100% akadama but I couldn’t use that with my indoor chilli bonsai as they would have dried out too quickly. I used a bit of a compost/akadama/kyodama mix … which works well (as long as I’m there to care for them) because it retains the water for a little bit longer for the drier, indoor climate.
I began looking into ways of using a sensor to check if it was dry before watering them and found it was not as hard as I thought. So I opened up my automatic watering kit and removed everything except for the pump. I replaced the cavity with an Arduino microcontroller, soil moisture sensor, relay unit and timer. 
The program reads the input 30 times and then divides it by 30 to take an average reading (and avoids any erroneous reading spikes). If the moisture level is below a certain threshold it turns on the pump. Because I didn’t want to have to re-calibrate the kit for every size pot I programmed the system to turn the pump on for 1 second, wait for 10 seconds (to allow the water to propagate through the soil to where the sensor is) and then to take another reading … this would loop until the sensor reads a moisture value that is above the threshold. After testing with my largest and smallest plants I found this method worked well (for the smaller plant it would only run the loop once or twice … and it would run it a lot more times for the larger ones).
The LCD timer controller just turns the lights on or off like any normal light timer controller.
I’ve drilled holes into a Spanish slate tile and fed the watering and soil moisture sensor through them to tidy the whole thing up, I also screwed the light holder into one end of it. It’s looking pretty good so far.
I've yet to actually figure out how much power this is drawing ... but its not much, the light is a 5W LED and theres not much driving Arduino controller and pump. I'll be sure to post the total consumption once I've tied everything down. 
I'm halfway through and I've been asked by quite a lot of my friends to create the same system for them (not just for bonsai enthusiasts but people with normal pot plants) so I decided to try to make a standard product of it. Once I've put together the final design I will be looking into bulk buy prices and then I will put the project onto Kickstarter to try to raise the capital.
Areas of  development (posts to follow):
  • Spread the irrigation system over the surface a bit more (as at the moment it is concentrated in one area … obviously I want to keep the moss moist as well as the soil).
  • Add a "misting" system which will run up the main trunk and mist the plant from the inside, everyday (independently of the main irrigation system)
  • add a “normal” set of LED’s that can be switched on in the evenings to “present” the plant.
Are there any other features you think would be a good addition?