Tier three- human scrap. We already kind of have an idea of what will be tier three tools and weapons, as we have already seen the mint mallet (the marksman's cap doesn't count as the armor tiers is more broad and random.) The mint mallet is made out of old mint chunks. It is also made out of high level nature items. This could be the same for all the other tools and weapons. For example, a charcoal hammer. It would be made out of (you guessed it) charcoal pieces and a paper stalk (more on that later.) You could then use the charcoal hammer to break glass. It could be used for arrows, a spear, and an axe. All these tools' handles would paper stalks. These would be made out of paper bits (which you could maybe find in the shed and would cut up with a tier two axe.) You would use two of these and one copper fiber to make one paper stalk. You would find copper wire inside broken plastic wire and would be able to cut it. You could then soften it in a forge/ oven, thus making it copper fiber. I don't know what the bow would be made out of (most likely some bendy human garbage; maybe a wire bow?) The dagger would be made out of some venomous thing from a bug somewhat harder than the wolf spider. The armor would be a mix of random scrap and rare items (maybe we could see more items that could be broken apart- like m&ms and popcorn.)
Tier four- small animals/ big bugs. Things like hummingbirds, scorpions, roaches, katydids, lizards, daddy long- legs, and centipedes would be cool. You would have to be more creative about the way you kill these creatures, as you could not fight them straight on. For example: You could arm an old mouse trap to kill a mouse. You would weaken a roach with roach poison, then kill it. You could cut off pieces of a centipede. You could smash a daddy long leg's legs in, then hit its body and head. You could then use a daddy long leg to make a spear. You could use roach parts to make a tanky armor. Hummingbird parts could be used to make an armor that gives attack stamina, and could also be used for a bow. A scorpion stinger could be used for a tier four dagger.
These are what I believe should be the next tiers. This post is less coherent and more rambly, as I just wrote what came to me. Let me know if these are what you think the next tiers should be!