Plastic injection mould tools
Most plastic injection mould tools consist of an outer bolster, with the component on separate inserts set inside this bolster, the first consideration is longevity and quantity, should the component be around for a long time and a high volume be required the tool would be manufactured using quality tool steel for the inserts and be fully hardened and tempered, were it to be a fashion item with only a few parts required the tool could be manufactured in Aluminium, providing the material the component is to be made out of is not to aggressive as mentioned glass filled, this will wear the tool out rapidly and more so in aluminium.
All the criteria mentioned in the aluminium die-casting process would be required, each tool would need a feed system, this could be a tab gate, tunnel gate, bucket gate, curly gate, Italian gate (The gate part being where the plastic enters the component). Then how do we get the material from the nozzle of the moulding machine to the gate? We could use a sprue and cold runner, a hot runner, a three plate tool, a hot tip bush, or as mentioned an Italian sprue straight on to the component.
Each tool would require a cooling system, the plastic being processed is quite hot and liquid when forced into the tool under pressure and needs cooling to solidify, this usually needs to be as quick as possible so that the next cycle can be started, so efficient cooling is a must.
Finally the ejection system, this is to get the solidified plastic component out of the tool, and is usually the most problematic, the part can stick in the tool so hard that it needs burning out, on the other hand parts can stick in the wrong side of the tool where there is no ejection and may need snatching over to the ejection side of the tool so you can eject them out.
Above is a very brief description of Plastic injection mould tooling and Aluminium Die-casting the process and parts it produces are as broad as your imagination as are the tools that make the parts.