You can either drill for oil and make enough so you can build a petroleum HQ and upgrade to add a refinery division and then refine that oil in to plastic. You can get your sims educated and have recycling plants that collect metal alloy and plastic. The key is to take whichever way you can so you can just set up trade depots to import the resources you need to make processors and computers/TVs. There are a few different routes you can take to get to that point. I think Commerce divisions in a Petroleum HQ and Electronics HQ will allow you to import and export the resources associated with those HQs. Or you can have a trade HQ with certain divisions in the region to allow it.