In the USA, New Mexico architect Alfred von Bachmayr delved deepest into perfecting the straw-clay tumbler. Here, one of his early designs stood on concrete blocks on the jobsite. It utilized two 55-gallon metal drums fastened end-to-end, supported by rubber wheels, and driven by a conventional electric motor through reduction pulleys.
Simple, portable, quiet and as Alfred intended buildable by, say, a village welder with access to very common materials.
Alfred went on to make improvements in his designs. A number of builders own and operate his large trailer-mounted units made with 3-foot diameter plastic culvert rotated by a weatherproof irrigation boom drive-motor. Sadly, we lost Alfred in 2013.