Hi Andy.
The waterwheel was a kit from an American supplier (RRStoneworks) which I picked up on one of my regular trips to Florida. The sluice divider frames and control gates for the sluice were also from the same supplier - the remainder of the waterwheel i.e. the supporting structures, the sluice run and its supporting framework were just built up from balsawood, painted with wood stain and varnished.
I still intend to do some weathering to the water wheel, as it looks too 'new' at the moment.
Building the water wheel was very straight forward, apart from fitting the centre section, and I finally discarded the plastic centre (supplied with the kit),which joined the two sides of the wheel together, in favour of a scratch-built one in balsawood - painted in several coats of marine varnish.
RRStoneworks has a wide range of various types of model kits - the only drawback I suppose, is that they are American based, so ordering from the UK becomes expensive (not a problem for me fortunately, as I order them for delivery to my U.S.A. address).