We're nearing the release stage for our game and we've gotten to the point where we are working on optimizing everything for mobile devices. We want to try to support as many devices as possible, so we considered the idea of using sprites to replace our 3D models to save on system resources.
Unreal has a built in way to make what they call "3D Imposter Sprites" (also known as billboard sprites or 3D sprites) that are 2D sprites that look like 3D models from every angle (or just from one axis if you really want to save on system resources) because their surfaces are always facing the camera. This sounds great in theory, but I had some trouble getting them working when I was following the Unreal documentation. Here is my modified (and, in my opinion, clarified) method for creating 3D imposter sprites for your game.
Tutorial completed using Unreal Engine 4.7 Preview 5