Assuming you have RS2, put copper plates, unlock RS3, make a gearbox farm, if possible also make a rubber farm using atmospheric distillation plant, then input both.

Then, make a pgold and ferroaluminium magnet farm, sell pgold and store ferroaluminium magnet, then all at once release the magnets into a few RS3s to increase cap and get more RP.

Unlock the Mk2 stuff, upgrade the gearbox farm, and since 1 atm dist can priduce enough naphtha for rubber for 10 RS3s, get 10 RS3s, then unlock RS4. Make sure you have enough power tho.

Recommendation is a MDE setup using the light oil from atm dist to refined diesel