There has been a long running thread on heating your shop and several others on the same topic that I have been following for some time. I live in Wisconsin and have an unheated shop at the moment and very little gets done in the winter due to this. I am planning on insulation, new windows and doors and heat for next winter so I can work year around.
But the heat source is another question, I have been a fire fighter for 20 years and do not want to burn down my shop (would never hear the end of that) so I am leaning toward electric heat. But today there was an entry in the safely heating your shop forum that was a recycled pop can solar heater for $2750.00, a bit out of my price range so I did a goggle search and came up with this http://sites.google.com/site/brianshomebrewsolar/ .
The question is has anyone tried this to supplement there heat source? And what would be an alternative to pop/beer cans is I drink very little of either and would take years to collect enough.
I guess I am putting it out there to get some ideas, so I can build a small scale version for testing. I have access to countless size fans and a device to measure and record temperatures for the testing as well as more cold weather than i care for.