For the whitemetal industry it is almost exclusively the case that the patterns be made in brass. My first brass master was made for a very new company then, called Grand Prix Models. I'd suggested they made some kits and they agreed and asked me to make a master of a Trojan Chummy, that strange little pram like thing with solid tyres, much beloved of vicars and district nurses.
This is a 1/76th scale model of a Fairline 50, the company's one-time flagship. It is all in brass, with a little epoxy putty for the "water". The deck removes and inside are seperate cabins with all furniture, all also done in brass, right down to the turned-down corners of the bedspreads.
A 1/48th scale Jeep with trailer and, unseen, its cannon. Bits of its suspension and equipment can be seen in component form waiting for the caster's mysterious art.
And one of the smallest, but not quite. A master for an Alfa Romeo Spider to a "fit-the-box" scale, for a giftware company. I believe they were used for a motoring version of Monopoly. There was also a Damon Hill F1 car and this:-
A Rolls Royce Silver Ghost at an even smaller scale, being a bigger car, to fit the same box! The artillery spoked wheels were one of the most taxing jobs I've done on a brass master.
A complete 1/43rd scale brass master of a Berkeley T60 3-wheeler. It was one of the last complete masters I did before going to live afloat, where such things were not possible.
This selection barely scratches the surface of all the masters I have done. Not all were in brass. The Aston Martins at the top were carved from a resin toolmakers' material and given brass wheels and tyres with correct tyre tread pattern. They were then used by a silversmithing company to make silver copies to be sold under Aston Martin's giftware label for around £1000 each.
The patterns were rather more expensive....