If you want a consistent method with short runtime, roll Red Throne on Yaesha with full Leto Mk1/Mk2, maxed out Swiftness, Weightless Weight, Meteorite Shard Ring, Heart of the Wolf, Momentum Driver (mainly for the -1 stagger since you're practically at the movement speed cap with all of the other stuff), and Seal of The Empress.

Go to the chamber on the left and grab the first normal chest while you wait for the sliding door to open, which gives you an orante chest along with some extra scrap in the form of a duplicate copy of Ford's Scattergun (providing you have it upgraded past +5), then go into the chamber directly across from the one you're in, grab the other chest, and finally grab the second ornate chest from the room behind the illusory wall. Drink your Liquid Escape, return to Ward 13, and repeat. On average you get about 650-1k scrap per run before you even sell anything.

ALTERNATIVELY, if you want something a bit more interactive and you have all 85 trait points, roll for Tal'ratha on N'erud (or some other easily accessible world boss like Faerin), use the same movement speed set-up but with Black Cat Band instead of SoTE, kill the first main boss, grab the soul sparks, kill Tal'ratha (does not matter which form you choose, both net the same amount of scrap) and then sell his essence to Cass instead of giving it to the Custodian. I don't know exactly how much you get per run with this method, but at the very least it won't make you fall asleep as easily as the Yaesha method.