If you get the ruff and ready ones you can also use colored pencils on them. Though I have always found that Sharpies work best.
They are beyond easy to work with and fun. I started a tradition many years ago that as a family we make a new Christmas ornament every year. We Draw something that best represents the major events of that year. (Wedding rings for the year we were married, A house for the year we got our first house, etc.) It's become a favorite part of christmas in our house and friends and family always look forward to finding the new ornament on the tree.
It actually shrinks down to a 1/3rd of the size. Our ornaments are drawn on half sheets and end up about the size of my palm when finished. I will say this Once it's shrunken down those corners can get rather sharp. We always try to round them off before shrinking. The few we didn't can almost hurt someone. Also when using the ruff and ready (the only kind we like to use) Remember that the glossy side is the one you want to look at but you draw on the other side so you have to layer your detail backwards. We have found its best to draw the design on a piece of paper first and then trace it on to the shrinky dink. Also Outlining the SHarpie on both sides of the shrinky dink makes for a cool layered stained glass effect once finished.
Have fun!
