How about we tat something using a thread size you're not accustomed to using?
For example, I'm usually tatting with size 70/80 thread. I'm going to do Totusmel's Mask in size 10 thread (since this is the recommended size). And just for kicks, I'm also going to tat it with the thread I'm more comfortable using and put them side by side for comparison.
It doesn't have to be anything too complicated, any motif would do. Just do it with a thread size you haven't tatted with before.