An injection molder is the primary way to produce polymeric items in Polycraft. To use it, the desired mold is produced on the machining mill, then the mold, a bag of polymer pellets, and a fuel source are added to the injection molder. Only the type of polymer listed in the recipe can be used to make a specific item, i.e., the running shoes can only be produced using PolyIsoPrene pellets. A single item is produced at a time in the molder; to make multiple items connect the injection molder to a hopper below it. The hopper can then be connected to a chest to allow for more item production.