The Money Making Machine is an object found in The Vault of Strangetown Hotel in The Sims 2. It can be used in order to obtain more money, as 10 simoleons can be produced at a time. However, if caught your sim will be taken to Strangetown Jail and have to pay the 200 simoleons for bail, so there's a big risk involved. There is only one of them in the game, much like many other objects which are unique to certain rooms of the hotel.
The machine can also be used to process metal bars found with the Metal Detector in the Desert. Doing this rewards you with more money than you would get from selling them at the Store. Furthermore, bars of chocolate can also be processed in the machine, rewarding 3 simoleons for each bar processed, however chocolate bars cost 4 simoleons to purchase so it's an overall loss.