I sometimes have my sims use the woodworking table at the art center in San Myshuno if I don't have room/money to buy their own - making garden tubs cost 377 but they will bring in anywhere from 800 on the low end to 4700 so far for the high end (their mood when creating will effect the value) - painting is probably quicker but not with the mod that you are using. If they learn the schematic of the mascot in Granite Falls, they can do even better, but that involves a trip to learn it.
The easiest and fastest way to earn money that I have found so far without any necessary skills is the music mixing table - it's quick and I believe only a 12 hour turn around time before you can release more music.