Not sure you can actually cast titanium; if you were able to melt it you probably wouldn't need it, if you know what I mean

You could do simple lost-wax casting with a variety of materials, the cheapest of which would be to cast white metal. However, the quality of this is debatable. Casting Aluminium would require a seriously expensive electric smelting oven or furnace and has explosion risks (Al spontaneously combusts under certain conditions near its melt point). It also requires a lot of finishing on the finished article as what comes out of the mold is pretty primitive.

One nice alternative is resin casting, which would give a good quality finished product without much finishing or great expense. You could mix Alu or anodised powders with transparent or coloured resins and cold cast it. It is pretty noxious stuff though and requires a lot of precautions to handle it safely.

You could always spray paint the buttons silver....

One of the few remaining Mk1 owners... #00015