I wanted to echo Carl's post about using a basic drum to make charcoal. An unmodified 55 gallon barrel works great as a 'flame cap' burner. No cutting, no welding, no modification of any kind.
Tip it a little and feed gradually.
Save yourself time and money and give it a try!
"flame cap" is an important search term.
Video of unmodified drum char making:
Some links to 'flame cap' burners:
Flame Cap tub burners
Small scale biochar kilns
ChuckW
