Harrison Krix is one talented, talented guy. First, he made that amazing replica Portal gun. Now, he's made this amazing replica ADAM syringe, "weapon" of choice for the Little Sisters of 2K's BioShock.
There's a step-by-step breakdown of how he made it at his website, but we'd just like to bring to your attention this little detail included near the end:
A key thing missing in almost all of the syringes I've seen so far is the baby bottle nipple end on the ADAM chamber. You can watch the Little Sisters drink from it in the trailers... gross. The ring was made from apoxie sculpt and PVC, and the clear nipple painted pink from the inside. It recieved the same weathering treatment as the rest of the syringe.
Krix, of course, included the nipple, which you can see in all its grisly detail in the gallery below.
Bioshock Little Sister ADAM Syringe [Volpin Props, via Dtoid]