Металлолом

Scrap doesn't have a gathering node or a craft recipe — it comes from crates, barrels, recycling almost anything, and NPC loot. It's the one resource you can't just go mine or farm directly.

Recycling is the biggest source for most players

Nearly every item in the game gives some scrap back when recycled, which is why clearing your inventory of junk at a recycler before a wipe reset or after a loot run adds up fast. If you're not sure whether something's worth keeping, recycling it for scrap is rarely a bad default.

Crates are the fastest single hits

Military Crates give 8, Elite Crates give 25, and Locked Crates (the ones needing a key) give 140–159 in one go — locked crates at monuments like the Dome or Water Treatment are worth prioritizing purely for the scrap if you're geared enough to clear the scientists guarding them.

Barrels and NPCs add up too

Barrels only give a couple of scrap each, but they're everywhere and low-risk, so they're worth breaking on your way past even if you're not dedicating a run to them. Scientists at Bandit Camp, Outpost and the various monuments also drop scrap when killed, on top of whatever gear they're carrying.

What it's actually for

Scrap is the currency for research, the tech tree, and NPC trades at Bandit Camp and Outpost — it's arguably more valuable than most raw resources, since you can't substitute anything else for it when a blueprint costs scrap.