How to offset flex item?

I'm developing a pure flexbox grid framework called flexboxes. I'm looking to implement a way to offset flex items by a particular number of grid columns in any flex-direction. This is possible with percentage margin but can it be done in a simpler way using flex properties? With what's available in flexboxes@0.4.0? I'd rather not implement margin classes this way because doing to would seemingly require adding classes for all 4 directions to accommodate all flex-direction values.