Biff Frith was a stalwart of the MCG Diggers until his death in 2017, and he would always come up trumps with specialist equipment for our digs. If we ran into a problem you could rely on him to create something special to overcome them.
For instance built two monorails for spoil extraction and they were installed in Carcass Cave (Axbridge Hill) and Battery Swallet. The first photo shows Biff with the one in Carcass Cave, where much of the digging was done with an air powered chisel. This of course required a compressor to operate, and for various reasons this could not be left on the hill. Given that the hill is somewhat steep, and the compressor very heavy, Biff simply converted said compressor into a self-propelled unit, as shown in the second photo. The final photo shows Biff and Whitelackington (for those who remember him on UK Caving) with the compressor and air chisel outside Carcass Cave.
We still miss Biff, and I ma pretty sure if he was still around we would have no need to enter this competition as he would have built us something comparable. Alas none of the rest of us have his Scrapyard Challenge engineering skill so we could really do with winning one of these items!
Thanks to Bill Chadwick for the photos.