These are just some simple coordinate axes. I'm the kind of person that needs to have a thing to touch and manipulate when I'm thinking quantitatively in 3 dimensions, so I find having this sort of thing helpful for doing vector coordinate transformations and that kind of thing.

I included axes labeled (x,y,z) and (u,v,w). My recommendation is that you print (x,y,z) in 100% scale, and (u,v,w) in 75% scale so that if you are imagining a coordinate transformation, the (x,y,z) system is the base coordinates and the (u,v,w) system is the primed coordinates.