Sorry for my poor english, I'm a french guy. I have a lot of audio K7. Even if this support seems to come back a bit fashionable, I have enough to do to make the recovery, including a lamp shade to play with transparency. I had seen a tutorial to recycle K7 lamps but one had to buy a foot lamps (http://www.forumbrico.fr/fabriquer-une-lampe-avec-des-cassettes-audio.html). I was a little further in recycling with an electric recovery kit and a plastic CD sleeve.
Step 1: Material
Budget: 10 €
One LED bulb
A rigid CD or DVD sleeve
An electric kit (cable + socket + switch + socket)
12 to 16 cassettes
Step 2: Lamp Holder
I chose to insert the support of the socket between the 1st stage of cassette audio and the 2nd. I also chose to use a rigid plastic CD or DVD sleeve but you can very well use a 126x126 mm board or other support.
I cut in the pocket with a cutter to have a square of 126x126mm. It is enough to dig well with the cutter then to "break" to cut. Same to make the hole in the E14 holder. You can also use a dremmel to drill, it's simpler.
Once that is done, we go to the next step.
Step 3: Realization of Floors
It's very simple, just stick one side of the casseette to another cassette and so on for each floor.
Make independently 3 or 4 floors by shifting the glued sides: the 1st floor is the right side which is glued, the 2nd the left side, ...
Be careful , the superglue sticks to the fingers and it sinks. Protect the work surface.
Step 4: Installation of the Following Support and Stages
Take one of the floors and glue the support on it.
Then glue the additional floors, with the left, right offset.
Place the socket on the holder. Make a hole in one of the bottom cassette to let the electric cable through.
There you go !