Working with silicone was always a big mysterium for me. I wondered what you have to do to come out with a good result. There are so many things that can go wrong. But guys I never would have thought that it can be so easy.
Trollfactory is suporting this video with a package of needed materials so that I can try out the procedure and also can test different silicones. If you want to know more about the products please visit the website at https://trollfactory.de/
I made a 3D print of the knobs and covered them with some coats of sprayfiller. Then I made a silicone mold and used a quick hardening resin to cast the knobs.
For the final color I used RAL 7047.
I also made a smaller wooden silicone holder which made it easier to mold small things like these knobs. You can download the sketchup file for free.