The 2 x 4's run through the kennel, through the fence panels.They are spaced just far enough apart so the barrel sits in them but not fall
through. Screw the barrel to the 2 x 4's. Cut a piece of plywood for the platform and screw to the top of 2 x 4's. You can see a little
better in this pic how the 2 x 4's just slide through the fencing.