I recently purchased a product from EZScreenprint that will allow anyone, and I mean anyone (even a monkey like me), to create a silk screen of any black and white image to transfer onto pretty much any surface. All you need is a nice sunny day to develop your stencil.
They are marketed mostly to fabric people who want to print on their fabric creations, but they can apparently be used on POTTERY.
I splurged and bought the starter kit, but as shipping costs were ridiculous, I got an additional pack of 3 sheets to make the shipping cost worth it.
Anyway, I have been scrounging the internet for good designs, patterns images as well as drawing my own. I think I have come up with some really good ideas, but needed to know how much detail would be captured, how bold the lines need to be etc so I used the test piece provided in the kit and one of my own little drawings and this is what I got. Now I need to see if it actually works with the underglazes I have and will give it a shot tonight.