For most of my life, I didn't experience any feeling from physical contact with my nips. Recently though, like unlocking a talent tree ability in an RPG, this part of my body suddenly ... activated.

Now that this "awakening" has occured, the nips are sympathetic to many levels of stimulation on a spectrum ranging from pain to pleasure.

Just like moles and bithmark, a lot can go unnoticed about your own body if you don't think to explore it. This peripheral is a reflection of this noteable sensory discovery.

So, if this sounds a little funny, let me attempt to put your head in the same place mine has been:

• How big can your nipples get? I'm serious. Do you know?
• What circumstances cause them to get stiff?
• Is it seemingly random?
• Is there a relation to sensual stimulation?
• When it happens, do you find it pleasurable?

All of these things I had never considered until recently. Like any good feedback loop, the more I concentrated on my own awareness of these feelings, the more intensely I felt them... and thus, my curiocity grew.

If I were to detect some physical change from this part of my body that gives me visual feedback of stimulation, it would have to be size.

So the question became, "How can I create a system that makes me aware of my nipples and when they are changing in size?"

I chose to investigate how I might track subtle fluctuations in growth.

For the first iteration of the propeller pasties, I played with a couple of IR distance sensors. They send out an infrared light, and depending on how long it takes for that light to bounce off a surface and come back, they can tell how close or far something is from them. If held directly above my nipple, they can sense even very slight changes in my nipple's girth.

This apparatus leverages the IR distance sensor to spin a propeller at a rate relative to the nipple's size (distance from the sensor).

As the propeller spins, the mechanism that provides for the spinning motion is also equipped with paddles which massage the areola of the nipple... creating more stimulation to the nipple and encouraging further growth.