Painting pupils on resin eye blanks.... thoughts?

I'm curious to know how people have painted nice neat pupils on resin eye blanks. I recently tried making my own stencils, and while the results were pretty good (better than drawing them on using a circle template) I wonder if there's an easier way... here's my blog post about it here. http://www.sanssoucistudios.com/blog/painting-pupils-on-resin-eye-blanks

TIA!