I always wanted an injection molding machine, but even the small machines have significant setup costs and space requirements. There’s also quite a learning curve on mold-making and materials handling. I stumbled across the book Secrets of Building a Plastic Injection Molding Machine by Vincent Gingery. This looked like a good project to play around with injection molding, without the huge investment.
David J. Gingery Publishing has long been know as a source for information on industrial arts like metal working, foundrywork, and more. I remember it being a big source of DIY info for Makers, before YouTube was even a thing.
In any event, I went through the book and learned a lot. I was happy with the way it turned out.
I made a mold for the plastic knob, used to raise and lower the machine’s table. This is described in the book. To test it, I melted some 20oz. plastic soda bottles, and made a few different-colored knobs:
I cut the electrical covers out of some thin sheet metal. The outlines for the shapes can be found here: