I was in b&q and I spotted one of these:
It was reduced down to £1.50 – but I can only find them in store not on the web, so no linky I’m afraid!
The cube light is pretty small at around 5cm each side, but produces a fairly nice light.
To remove the bottom part requires a bit of force as its glued in place but once you do pry it apart you are presented with a single LED with two legs connected to a switch, then a 22 ohm resister +/-5% followed by 3 * 1.5v AG13 batteries. It looks like this:
At this point I realised something clever must be happening– all of them colours via only 2 pins! If you look very closely at LED you will notice on the top of the anode leg inside the led a tiny black dot. That dot is what controls the colour, so hacking this is going to be extremely limited if you intend on using this LED.
Whilst it’s currently driven from the 4.5v provided by the batteries I did successfully drive the unit from the 3.3v from a neduino board , so you could very easily use it as some form of output. Powering it externally also means it will last a lot longer than the 6-8 hours the leaflet expects it to last from the batteries – and given the batteries cost £1.89 from Amazon (more than the device cost!) it’s a good job!
I think that the best bet if you were hacking this device would be to replace the current in place IC controlled LED with a RGB LED. The plastic Plug holding all the gubbings also comes with a hole which could easily fit any cables you needed to bring out of the device!