[jacquesm]

You can do this with a lead crystal as well (that's how in the old days the diodes for crystal receivers were made).

Even a dirty razor blade and a pencil will work as a diode!

[kropotkinlives]

Yeah that was where I started with the idea and then decided to see if I could dope some silicon to make a diode then move up to transistor level, then a simple IC.

You could knock up a point contact diode or even transistor without too much pain but that's not as much fun :)

There's info on how to make point contact devices in here: http://www.qrparci.org/wa0itp/csts_book.pdf