I can’t figure out how to apply a texture to a cube so that it doesn’t stop when it hits the edge and create clear seams. If I were painting it I would just fade the edges and make them look worn down like most objects are, but I’m new to texturing so I just simply wanted to add a metallic texture to a cube but no matter how I unwrap it, there is always a very obvious edge, the texture won’t flow onto the next face.
You could just paint directly onto the model, and get rid of the seams that way. That’s how I usually approach a game asset. Here’s a quick video using cycles for texture painting. But there’s plenty on Blender internal if that’s what you prefer.
If it’s for something internal to Blender and the look isn’t specific, then you could try a procedural texture that doesn’t require uv coordinates. Someone else would have to describe that process to you though. But it is possible. 