It's not a perfect, nor complete reference., but it allows me to better judge proportion against the smaller heads. I recommend this technique to anyone who's having trouble with getting small statue heads to look right. The problem that comes up otherwise is that you wind up reworking the Sculpey over and over as you try to find the right proportions, all the while warming it into mush and making it harder to work with.

A larger scale won't change consistency as fast, and lets you use larger tools and your fingers (really the most useful tools of all) to find exactly the proportions you need. Afterwards, transferring the same look to a smaller scale is easy, as you can view the larger head from any angle and quickly see exactly where the problems lie.