John Spencer used to make his own from a f4 or F5 fosters dinghy section with a alloy drum welded to the bottom and Nolathane buses inserted in the top and bottom they were a bit agricultural bot the worked I thing thee were 2 pieces of section with a sleeve in the middle to join them and bushes in the sleeve also he did this as it was cheap .His own 32 had it on it (Hey Jude)