The Geiger counter is made from a kit, I cheated!

But it is a well put together kit with all the features one may require.
See here for more details: https://sites.google.com/site/diygeigercounter/

The Geiger Muller Tube i'm using is an BOI-33/STS-5.

STS-5 Tube

A graph of volts vs cpm for the tube i'm using:

BOI-33/STS-5