1. Have a successful artist sim that doesn't use career tree.
2. Max out the mansion baron aspiration using arts only.
Assign your sim one negative trait and two normal traits .
1. You must spend all of your initial funds on making a house/shack and equipping it.
2. You cannot "pawn" anything you've already bought in build/buy mode. It's yours forever. Plan carefully.
3. You can only make money by using a creative skill object. Carpentry, guitar, piano at the bar, moonlighting, writing, or painting.
4. Do not select a career for your sim. If you want them to have a significant other, have them have no job at all. They can have children/adopt.
5. Your sim has to do their own cleaning. No maid. You can stack dishes by the sink, but they must wash them themselves.
6. You are allowed one "kaching" per child your sim has. Let's call it welfare. Otherwise no money cheats.
Note: Don't assign your sim the ambitious trait unless you want it to whine ceaselessly while doing this challenge.
I've done this before and it's harder than it seems even with full money- the bills pile up very quickly with a normal size house.
1. Your sim dies of malnutrition or anything poverty related.
2. You cannot complete this within one lifespan.