There are two basic types, the twin vertical: similar to the Victorian silos, and a four cell plus design, that is, the smallest, like at Keith, is a four cell, or South Australian Bulk Handling added extra twin cell to increase capacity. Same design, just more cells. (The silos at Roseworthy are different).
|Sorry, slightly off center, but the edge of the scan is the edge of the cell,|
Bunnings sell PVC pipe by the meter, and if you are careful you can get a near straight cut. At least one end will be square cut. My model is not (will post photos soon). I found it was easier to screw to pipes together with some self drilling screws, top and bottoms, but make a wooden block to hold them in shape.
Coonalpyn has ten cells, plus two steel bins.
Tintinara has 8 celss.
Drawings for two cell silos. (I have left these a larger file size).
PS If anyone is modelling QR, they have silos that almost the same design as the SA ones. The first link is for Dalby, and the second, Wandoan.