Single pass outline shader

I’m trying to render the outline of a cube without diffuse, and I cannot seem to find a solution that allows me to render it as a single draw call such that can be batched. I’ve tried a number of outline shaders from the web, but they all involve a second draw call and thus can’t be batched. Is this feasible to achieve? Are there alternative methods people have used to simulate the desired behavior?

I think the reason why the only outline shaders you’ve found require two passes is because that’s the only way it can be done…