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)
Glue
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.