First of all, please bear with me, this is my first instructable ...
It all started with me browsing through Instructables and finding a lot of great ideas. I came across the CapSense Arduino library and this great instructable, and just had to try it out. The idea behind is you create a proximity sensor using just aluminum foil, an Arduino and a 10 megaohms resistor. It is very easy to put the peices together even for an electronics beginner as myself. I got it started and a LED was blinking based on the proximity of my hand. As soon as my kids saw this, it was not my project any more, and I had to stand behing letting them play with it. I got them to back off only by promising them a magic orb based on this ... ;-)
Step 1: Magic Orb - the looks
Putting aside the electronics part for a moment, I had to create something interesting for the kids. Since I am also a big fan of bioluminescence (Avatar style flora, etc.) I thought of an elven magic orb, a wooden log style plant.
First I created the shape with Blender (find the blend attatched) and exported as DAE since this seams the most accurate format which can be used in other 3D software. At least with Pepakura it was so. This is what I used (Pepakura file attatched) to convert the 3D object into printable peices which I then glued together (see first two pics).
The cardboard I used (I think it was 180g/m2) was hardly strong enough so I had to harden it somehow. This part is a little bit more tricky. Usually you take some resin to do that, but since all resins I could find until now are toxic and had to be handled carefully with masks etc., I just went with paper mache for the first layer. A big mistake I made was cutting the holes in the cardboard before putting the glue and paper on. As soon as I started with the glue, everything was soft and almost "melted". But I saved it as soon as the glue was half dried, and formed it back. By the way I used wallpaper adhesive for the paper mache.
Then I put two layers of gypsum bandages. This turns into a really strong form, but still breakable. But since almost any lamp is breakable, it was good enough.
Step 2: Electronics
Like mentioned in the intro, the core elements of this part are an Arduino, aluminum foil and a 10 megaohm capacitor.
Then I got a bit stingy and didn't want to use my only Arduino Uno for this. Another instructable caught my attention. For easy controlling an Attiny is more than enough, so this can be used to programm it using an Arduino with the same code tested on the Arduino. The Arduino code is also attatched, nothing fancy. It only monitors the input of the aluminum foil, and brightens the LEDs more if input is found. If no input the LEDs fade away. If the input is long enough, the light stays on. Didn't mention it, I used a simple 12V LED strip with 12 LEDs.
Now I had to extend the layout a bit, because the Attiny uses 5V and the LEDs used 12V. Since I didn't want to use two current inputs, I used a 7805 voltage regulator and two 10uF capacitors. Also because of the 2 voltages, I used a TIP122 transistor to control the 12V LEDs using the 5V output from the ATTiny.
Since I am an electronics beginner I look forward on your comments on mistakes or possible enhancements.
I can only say one thing ... It works so far ... ;-)
Step 3: Putting it all together
Almost finished. I used a round peice of wood as the base of the lamp (also good for stability and holding all electronics). The aluminum foil I glued on the inside of the lamp. The same with the LEDs. The little breadboard I glued on the base. I also used an adapter for the current input, and a little power switch at the bottom to completely turn the lamp off.
Finally I painted the outside too look like some kind of tree bark on grass. My first time to paint tree bark. Not as easy as I thought ;-)
So I hope you enjoyed it, and please suggest in the comments anything that comes to mind. I would gladly improve both my magic orb and this instructable ...