If you are reading this, then you are probably always out of money. It happens to the best of us. You absolutely have to have those Leaf Wings , and suddenly you don't have the platinum coin to spare. Making money is simple and hassle-free enough if you know how to go about it.
This strategy works in both Hard Mode and Pre-Hard Mode. You will need a boss spawning item of your choice, and the required equipment to defeat the boss. Any item that increases the coin drops of the boss will help too.
How to do it
If you don't have one already, build an arena.My Arena-Building guide will be out soon, so check that out. Summon and defeat the boss; when writing this I have already posted guides on defeating the Eater of Worlds and the Eye of Cthulhu, geared towards beginning players.
At this point, you should have gotten about 2-6 gold coins, which is the average drop of a boss. Don't worry! There's further to go still.
In Pre-Hard Mode, craft all your Demonite/Crimtane ore into bars. Sell them all to the Merchant, and you should have about 12-15 gold coins.
Selling all the Hallowed Bars and Souls gained from a mechanical boss fight should yield a grand total of about 18-25 gold. If you sell any valuable extras the boss may drop, such as the Binoculars from the Eye of Cthulhu, it'll grant you even more.
Of course, this is only one strategy of farming money. Boss farming can be time-consuming and many bosses can only be spawned at night, leaving other night monsters such as Zombies in Pre-Hard Mode and Wandering Eyes in Hard mode to harass you while you are trying to fight. Of course, if you are well-armed enough to be farming bosses, you should be equipped enough to deal with these additional hazards. This includes a good-quality arena.
Another strategy is wiring statues to timers and waiting a while, then coming back to sell the drops. The money you make from this depends on which monster you choose to spawn.
If you couldn't be bothered to read the entire thing, which I can fully understand, here is basically how to farm money: kill bosses, craft the ore into bars if possible, sell the drops, rinse and repeat. An hour's good work can lead to about 30-50 gold coins, depending on which boss you are fighting and whether it can be spawned during the day or not. The Eater of Worlds is an especially good boss to farm due to its many segments providing each its own ore and coin drop