Here is side view of my stove. Notice the cobbled together construction. I picked up the 30 Gal. drums for $3 each, the primary and secondary burn chambers are welded together from scrap steel and some purchased pipe and steel bits. The scrap steel cost me $7 and I've still got quite a bit left. The actuall burn chambers are contained within the 30 Gal. drums, with vermiculite insulating between the two.

Currently the whole unit is sitting on an oak platform, on 4" casters. This makes it easier to move around while things are still under construction, but makes it difficult to secure the stack.

It is easy to see that I did not fit the barrels together as well as could be done. I've used flashing to fill the gap on the top of the left joint and good ol' duct tape on the other joints. The duct tape is not holding up well as the exterior of the barrels gets far hotter than I'd expected, and is melting the duct tape.

Here's a top down view of the fuel chamber lid and primary combustion air inlet. I used 2" pipe for the inlet and an end cap to damper it. I cut notches in the pipe to allow some air in. Screwing the end cap further on decreases the amount of air allowed in, while opening it further increases the avaliable air.

Here is a view of the front of the stove. The door is hollow and filled with vermiculite for additional insulation (I think this was unnecessary, as the steel conducts heat well enough to make that a non-issue. Again, I've used a 2" ID pipe with crenelations for the air inlet, and another end cap to damper it. In this case I've found that the 2" pipe is barely adequate and I rarely use the end cap. I'd like to add a blower to increase the air flow. I'm also looking at building an air to air heat exchanger to pre-heat the combustion air, from flue gas, after the primary air to water heat exchanger.

This is a close up view of the secondary air intake, showing the flaming gasses inside the secondary burn chamber, this is across the bottom of the unit, before the flue starts up.

Epilogue:
I used it one winter to heat my work space.

Lessons learned:
1. Steel does not stand up to the flame/heat well.
2. air flow control is CRITICAL