I thought it might be interesting to have a discussion on this fascinating  topic that I am a rookie at but have been doing and learning about.
I first gathered all the information I could get from Oscar Gaddy's writings, who I understand has gone over the great divide, and begin to assemble all the various hardware and equipment needed to make this happen. 
It took me two tries to come up with the crucible shape I wanted for single shot and Mauser rifle actions. Gaddy always used stainless pipe but I made my in rectangular form using channel iron welded together. 
  Gaddy mostly did shotgun actions but single shot rifle actions are so similar in size and shape I found the information universal. 
  I used Brownells charcoal but have been collecting moose and caribou bones to make my own so as to avoid the hasmat  fees to Alaska.
  The Uberti case job did not turn out as striking as several others I have done but when drilling and tapping a hole in the upper tang I found a very satisfactory improvement in casing depth over the factory job as well as an improvement in color. The case is several thousands deeper and the core still soft.
  So far in my limited experience I have found that a 50/50 mix of bone to hardwood charcoal to produce the best results. 
Several things are critical to get right for safety and color.
1. temperature/ duration 1325 - 1400 degrees F. , 1. 5 hours at full temperature
2. depth of drop to quench 2-3 inches
3. Aeration of quench water
4. charcoal packed around all metal parts and no voids
  All parts should be braced correctly to minimize warpage. Side plates and bolts can be added to somewhat control color pattern and placement.
  It should be alway kept in mind that the most important reason for casing is strength without brittleness to carbon steels and color is secondary. MD

The tree is a good idea and I have not used one before because of the small size of my crucible but you got me to thinking that perhaps wiring the parts together with the half inch of charcoal separating them may not be a bad idea, insuring everything going down the water column together and not banging around. Thanks for the tip. MD