This is some kind of crazy idea, and I am not sure it would work. If someone has good knowledge of mechanics and thermodynamics, please read and tell me what you think about that.
I love the idea of perpetual motion. You have to give an initial force, and then a movement is created that will never stops. Real perpetual motion is hard, but an almost perpetual motion would certainly be enough to power a light bulb. We can use for instance the principle of the Orffyreus Wheel :
How Orffyreus Wheel works :
There are 5 smalls balls inside the object. The moving of the balls inside the object provoke an unsteadiness that maintains the movement. During the lurching of the object, energy is partly lost. I propose to attach some other wheel to the object so we can use this energy lost to power something.
How would my object work :
1/ pushing the button to turn the light on is the initial force (so no other energy required at all)
2/ it sets the mechanism (described above) in motion : this motion will be maintained then and be used to create energy during several hour (not always as I think a perfect perpetual movement is too difficult to create)
3/ this energy is linked to your light buld, and that's it !