I have an inventing tip for the insane, almost got my dynasty sim kicked out of China but was worth it for the sheer fun, did the same thing in Rica's challenge but at home.
Basically buy a lot of the cheap portable stereos, line them all up, I put them in rows of ten then detonate somewhere near the middle, don't do it too near anything you wish to keep as fires break out and keep your sims well clear, for Rica's challenge I lined up the full amount for diabolical detonator and I think it was just 38 that didn't go up first go, serious fire hazard but such fun watching them go off like dominoes
Had a job getting her to collect the scrap though as her motives bombed from the vile surroundings but if it's your home lot dragging them into inventory still counts them on the scrap collected total.
It does take a while to max as a career but for the two challenges, scrap collector and diabolical detonator, they can be got fairly fast this way, but it is a bit dangerous so best done well away from everything and everyone.