Glenn Herbert wrote:Are you thinking of the 5-gallon cans (stacked) to contain the heat riser insulation? I believe those would work fine. You would probably want to burn them off outside first, as the outer skin of the riser will mostly not get hot enough to burn clean without long hot fires, if then. I would not try to use them as the outer barrel in a scaled-down J-tube system, as such small-scale systems are supposed to be much harder to get working well than larger systems. I would try a 6" system for starters, as that will work if you get close to a correct build.