I use to be intimidated by freehand piping but it can be easy if you draw your design on paper or print an image from the internet, you can use a sharp object (I used a roasting pin) and press it into the icing so you have a basic guide.
Place your image on top of a dry cookie
Gently press the roasting pin into the royal icing to make an indention
See the holes the pin left?
Pipe on top of the holes
And there you have it.. A perfect pair of spectacles!
Well almost perfect, see my boo boo ^ I missed covering a few of the holes
Have you tried this yourself? Do you have an easier way to do this? if so, let me know