Puff paint would probably work, but I still won't be able to make pen width lines in geometric shapes. Perfectionism is a curse in so many ways. There are pre-made computer cut vinyl stencils, but not in this shape.
The "bizarre stipulation" is... just too weird. This probably isn't the right thread or forum section to discuss it, but it has nothing to do with anything RayN sells so I hope it's alright. It comes down to a moral dilemma in which I have to decide how greedy or modest I want to be. Imagine a scenario in which I offer you free e-liquid but nobody has had it before and there are no reviews. You can have anything from 5ml to 250ml. What do you do? Why am I making you decide?
edit: @glassmanoak- I did my test on a scrap piece of flat glass. I seriously doubt I could transfer such thin cuts of contact paper.
The design is essentially one piece of contact paper. Cut all the way through the backing, and peel it off the tiny design and stick that to the tank. Worth an experiment! I need a fatter design, like a simple star.