[s1mon]

At one point aluminum tools were a good trade off in time vs quality, but these days they only save maybe 10-20% of the tooling schedule and cost over steel. Tool life and robustness isn’t great so they’re not so popular any more. Usually when someone says “soft tooling” these days, they just mean softer steel which is slightly cheaper and faster to machine, at some trade off in tool life.

There are already 3D printed steel core and cavity inserts for injection molds. They laser sinter powdered metal and then run a very tiny ball end mill around each layer to clean up the surface finish. Traditional CNC and EDM is still how most molds are made, but occasionally it makes sense to 3D print. You can get cooling lines in patterns that are impossible to machine and you can make tools faster sometimes. The costs for the machines are very high, and the size of the parts are limited.