The first step was to prototype the purely physical stage of the product. This means prototyping and designing a marker with several intersecting qualities related to taking ownership of a particular locale. The key features that I initially needed to design for come down to the following:
1) Visibility - Bright, eye catching, indicative of a user's goals and actions.
2) Resilience - especially to being soaked with water/urine
3) Conductivity - To measure the power of your pee with the arduino
4) Mutability - to provide a bit more engagement and feelings of accomplishment for the interactor, the device should react and change in accord with the user's actions (peeing on it makes it different)
5) Semi-Permanence - Littering sucks, and also this increasing the dynamics of claiming spaces; once your marks bio-degrade you need to maintain your trips and markings of a place to retain leadership.
At first, I wanted to deal primarily with points 1 and 2 (and a little bit of 4).
My very first goal was to create a little marker that, when peed on, would reveal a secret message.
A nice discussion of possibilities for doing this was held here:
My beginning attempts focused on methods of imprinting an invisible message onto supposedly ordinary looking paper which would reveal itself once soaked in water or a mildly acidic or basic solution (urine). This was the tricky part- there are lots of methods for making invisible ink that reveals itself when activated by heat or UV, but liquid alone proved to be challenging.
I experimented with those crayola color changing markers, and tried to located that special crayola water color paper used by very young children, where the colors are activated by a paintbrush with ordinary water.
The color changing markers failed to respond to water or urine in order to reveal the secret message. I tried various other chemicals too.
Another difficulty to this problem was that the method should be mechanically repoducable (i wanted to print it) and the message was of high visual complexity (a QR code), and I needed high contrast for it to be machine readable.
