Programmable Water (2003)
blikstein.com
blikstein.com
To build something we'd consider a 'computer' requires a huge amount of conceptual background. Boolean logic, binary arithmetic, memory, Von Neumann architecture... and to be useful, it really has to exist in a society with lots of things being recorded and tallied on paper.
http://www.personal.psu.edu/~tms9/Therapy_Waters.html
Also. Look everyone! Programmable electrons!