[Question] Custom decals

Guys, I had an idea. But I need information first :)

Has anyone here made custom decals? Or anyone knows how to make them? I want custom decals to turn this Dairy Delivery (or any Dairy Delviery or van I find) into a Delirium Tremens beer van :D

I want this

To look like it delivers this, in all its white, blue and pink glory: