Only Gilson Pipetman pipettes use the "P" prefix. Looks like you have a Rainin. Those use "R" prefixes. Also it's aspirate and dispense not withdrawal and expulsion. (Or at least I never heard those terms) Just a FYI. I sold them for years. Sorry to be a stickler. Good job on the constructable!
Bee and Beekeeping Projects
Tender Seitan Slices In Herbed Gravy
Redirect water from a raingutter to a rain barrel
Hack a Toilet for free water.
Make a Battery for a Rechargeable Mouse