Each month, the Reddit page for Blender holds a themed competition to decide the page's next sidebar image for the next month. I had participated a couple times with limited success. For the June, 2015 contest I received some additional motivation.

 

A man named Bill Moorier, an employee of Twitch streaming services, took interest in the contest. He offered a $100 prize to the winner of the next competition, provided they stream their process on Twitch. As usual, the previous winner chose the theme, which he described only as “Robot Heart”.

 

This is my winning submission: Mechanical hearts developed through the history of man, and into the future.