Mimics look like chests and seem to spawn relatively rarely. Is there an efficient way to farm them for their drops?
The most efficient way to farm them is to make a farm for them, of course! But while it's the most efficient way, it's still not very efficient. You could be looking at several minutes between drops.
The general setup for a Mimic farm is quite simple:
What happens: When a Mimic spawns in one of the tunnels off-screen, a Dart Trap will give it a poke, which sends it hopping towards you and ultimately, the lava pit.
Since this isn't a novel concept, here's two designs that I totally stole from other people.
Of course, there are also the general tips that apply to every grinder setup: