Start by researching copper ingots and vine goo at your research table then grab some seaweed from the ocean floor while looking for copper deposits near islands. Remember diving deep needs oxygen bottles, and copper's usually in deeper spots. Smelt your copper ore two-to-one for ingots, cook six seaweed for each vine goo in your smelter. Get your plastic from floating barrels while you're swimming around, you'll need five pieces.

Building multiple smelters makes everything way faster since you can process copper and seaweed at the same time. Once you've got everything ready, combine five plastic with two copper ingots and one vine goo to make two circuit boards. Bigger islands tend to have more copper, and if you're struggling with plastic try recycling extra equipment instead of waiting for barrels to show up. Might be interesting that circuit boards always come in pairs so plan your resource gathering accordingly.