Planet of Cubes (PoC) is a Minecraft-like survival MMO game on Android, and it has a P2W currency that lets you buy any gear you need.

Most everything is online, but there is an offline single-player mode which I haven't been able to figure out how to duplicate items.

I've tried GameGuardian, but no success with this game. Lucky patcher, no luck. I couldn't figure out how to use cheat engine, but I don't think CE works with online games anyways.

So, how would I go about finding exploits to either infinite game currency, or an item duplication glitch?

Search "Planet of Cubes" on the Play Store to find it.