[aerohead]

tooling can also be made with lath and plaster.The original Corvette tooling was done this way.
The 'plug' can be plaster as well as the female mold.Slit-molds for complex forms.
Georgia-Pacific makes a full line of industrial tooling plasters.
There's no 'stink'.No hazardous vapors.
Tooling epoxy, "plastic-faced" plaster molds can be used for limited production runs.
Even drywall compound can be used for one-off studies.After priming, painting,color-sanding,and polishing with acrylic lacquer and polyvinyl alcohol with three coats of carnauba wax,a perfect part or mold can be pulled.
Ferro-cement can also be used for tooling,even metal forming,but get help lifting as this is a 'heavy' proposition.
Beyond small batch production you'd want to graduate to Kirksite alloy tools.