Pipettes are prolific in laboratories everywhere and used to transfer variable amounts of liquid. Professional tools are calibrated and have dials that allow the user to set the volume. The following instructions are the result of an experiment to develop 3D printable and low cost alternatives to standard lab tools, such as the pipette. This simpler version uses a straw and allows the user to adjust volume using two limit thumb nuts. It should be very useful around any wet lab and works nicely with a relatively high range of possible volume settings. You can calibrate the volume but it is generally only good for low precision work. With the exception of a balloon or rubber glove, spring, straw, and some tape, all the parts are 3D printable without support using a variety of low cost printers. This is a very nice example of alternative lab tools and I hope will contribute to further work in the area. You can also find this model and some user remixes on thingiverse: http://www.thingiverse.com/thing:64977 
Print the upper body, lower body, plunger, and two thumb gears using a 3D printer, the STL files are attached. I printed all the pieces on a Makerbot Replicator 2 at 0.1mm with 15% fill and 100% fill for the plunger. You will need a spring, which I got from a kids Pez dispenser for its form factor. The balloon membrane or rubber glove is elastic so you may get away without the spring but it is nicer to have it. You also need some tape to seal the gap, and a straw. It is designed for standard straw diameter (which also works with the standard pipette tip) but I can upload others if there is demand, let me know.
Here how i made my vertical vegetable garden, starting from used big water bottles as planters. An automatic watering system keep the right moisture, collecting water in excess, using power from pv panels and a little wind turbine (vawt)
The green wall is composed by 72 water bottles cut and placed upside-down on a wooden shelf. 
I can't find on here the method I use to get my sterling silver rings sized JUST right, so here you guys go! 
Supplies