How to produce small plastic parts at home
Most people think that producing plastic parts is for big industry. That certainly used to be the case, but not any more! Modern materials have made it possible for anyone with a kitchen table to produce extremely high quality parts, out of a wide variety of plastics. This became possible with the advent of two different classes of materials. One is RTV Rubber, and the other is Polyurethane Casting Resin. RTV is a generic term that stands for "Room Temperature Vulcanizing", which means that the rubber doesn't need heat and pressure to solidify. Instead, it hardens up at room temperature. RTV rubbers typically come in a form that is the consistency of liquid honey.
Each one is different, but normally a catalyst is added to the rubber and mixed in thoroughly, and then the rubber is poured into a box with the original part glued inside. Typical RTVs take anywhere from an hour to 24 hours to set up, and when they do, you have a high quality rubber mold. It is possible to mold all kinds of items, from doorknobs to doll house furniture, to you-name-it! There are two main types of RTV rubbers, Silicone based and Urethane based. I recommend a silicone rubber for beginners, although it is a little more expensive. Use one that has a low viscosity, and is intended for hobbyists, as these are not so sensitive to contaminants on the original. They also don't require expensive equipment (such as a vacuum chamber) to get the air out once it's mixed. When purchasing Silicone RTV, ask your supplier for a "Tin" catalyzed RTV, not a "Platinum" catalyzed type. Tin catalyzed RTV is much less sensitive to contaminants than Platinum types.