In any case it was fun to just do something quick like this. Let me know in the comments if you would want this as a shirt and if enough people do I'll look into it a bit more.
Other than that the black lines are ink and the green lines are green gouache. To preserve the colors I had from the original scan I just converted the original scan into a multiply layer and colored under it on a different layer. Pretty good process for a simple piece like this.