I've spent hours trying to make a model of my own head with the intention of getting it 3D printed in colour in sandstone. First I spent hours trying to do it with 123D Catch - a free online service where you take about 40 photos of your head (or any other object) from many different angles, send them to the website and get a 3D model back that you can import into Blender. Problem: it doesn't' seem to work too well, for example every time you send the photos off for processing in the cloud you have to wait a few minutes for the model to come back, then you make an adjustment and send it back again ... the process takes ages. And you will certainly never get an elegant and accurate model this way.
After hours of searching, I finally found two videos that explain how to use 'projection painting' to project three or four photos of your head onto a standard head model that you have tweaked to match the shape of your head. See this 28 minute video or the silent 10 minute (speeded up) video below:
You can get a suitable model head to work with from www.blendswap.com, for example (free registration required).
See also this video.
Check back to this page in a few days to see the result of my efforts.