At some moment I decided that I want to build myself a 3d printer. Studying different rapid prototyping methods I found that I don’t like any of open sourced variants available. Well, there are actually two of them available:
1) Extruder head
2) Using off-the-shelf inkjet printer (but limited to off-the-shelf ink for it or, in some cases, distilled water)

Extruder head is just not fun. I don’t know why, but I never liked the idea. Inkjet printheads are fun, but really limited on viscosity of material(mostly, maximum you can do is 1.0 – 1.5).
So, time to build one yourself.
Basically, off the shelf inkjet printers has two types of printheads: piezoelectric or thermo. Last one uses heater element to heat ink (and on heating they expand) in limited volume camera with nozzle. Upon some point camera volume is too small and ink drop is fired.
Piezoelectric is way more fun. Too much words to explain how that works, but you can read a couple articles I’ve wrote some time ago:
https://sites.google.com/site/diy3dfab/general-...

Anyway, there were several prototypes I’ve created which never worked:
Here is first one, most dumb ever:

Well, it just never worked at all… now I know little more on topic and maybe I would have been able to make it work, but hell with it.

A little prettier one. Worked a little better then previous, but still failed the main idea – drop never separated from nozzle – it grew on it, with each pulse – bigger and bigger.

Well, there were lots of prototypes. At some point I had success. Drops started firing! Several pictures of the drops:

A little tweaking to achieve smaller and more consistent drops and finally:

Anyway, that thing still needs a lot of tweaking, and I am still working on it on my spare time…