Fun Ho! aluminium toys were made by a system known as green sand casting which, though simple in principle, required great skill in practice.
A pair of steel moulding boxes were used which had sides only but no tops or bottoms. A double sided plate with the shape of the toy to be moulded was sandwiched between the two boxes, which were then placed flat on the foundry floor.
A specially fine sand, almost like clay, which came from Dunedin, was shovelled into the uppermost box, the sandwiched plate forming the bottom. Sand was then rammed very tightly and levelled off.
The two boxes with the sandwiched plate were then turned upside down on the floor carefully so as not to disturb the compacted sand in the first box. Sand was then shovelled and compacted into the second box.
Carefully this box of sand was lifted clear of the plate, the sand remaining undisturbed in the box with the impression of the plate on the surface. Next, the plate was gently removed from the remaining box, leaving its imprint on the sand surface. Having removed the sandwiched plate, the first box of sand was replaced on top of the remaining box.
We now have two moulding boxes each tightly packed with sand, lifted together as one with a cavity in the sand equal to the displacement formed by the two sides of the plate.
A hole about 45mm (1 1/2") diameter was carefully made through to the cavity, into which molten aluminium is poured, forming the actual casting. After ten to twenty minutes of cooling, the casting was broken out of the sand in the moulding boxes and the cast toy became ready for "fettling." This was a series of procedures such as sawing the pouring stem off and filing any sharp edges or deformities.
The fettled and cleaned toy needed "rumbling" to smooth the surface, after which it needed drying off. Axle holes etc. needed to be drilled in place using a "jig" for accuracy. For painting, a wire "S" hook was passed through an axle hole and the casting was then dipped into a bath of paint, then hung up over a drip tray to drip dry.
When the paint was hardened, the stalactite drip of paint was cut off, and wheels and other fittings were put in place. After examining for flaws, transfers were added as and where appropriate, and another sturdy Fun Ho! toy was ready for the sandpit.