ReCore

This one is missable but it would be difficult to complete the game without doing this. You will be introduced to crafting new parts fairly early on in the game, after you defeat the first boss you will return to the Crawler and restore it's power and be introduced to crafting and upgrading.

Now you need need blueprints before you can craft the parts and can only craft one of each blueprint. There are multiple ways to get blueprints, the most common would be from chests scattered throughout the world which you will come across as you explore, the second is from the optiomal caves/dungeons that you can explore, most of these have optional objectives and from my experience, if you complete all of these you will get a full set (4 blueprints). The third is for doing the hunting challenges, which there is a bunch of for each of your Corebots, the will show up in the objectives tab down the bottom, these are quite easy but will take some time if you're not working on them.

The only other thing you will need now are the scrap that you see floating in the world and also get when you destroy Corebots.