How to mold silicone in a mold of some other material?

When I google “silicone in a mold” all I get are results about making molds of silicone for final parts in some other material. Unfortunately one cannot successfully mold a silicone part in a silicone mold. So what is the right non-silicone mold material for making final parts from silicone? I’m looking for something cheaper and faster than aluminum.

Thank you!

you can cast silicone inside a silicone mold if you use a release agent

you could also 3d print a mold although the silicone will pick up all the surface imperfections.

It is strongly recommended to not cast silicone in silicone as it will not set correctly and I received that advice after I tried it myself and got very strange results. Yes, I used release agent.