If you have always had an urge to mold something (small) of your own, and if you are near the Bay Area, Techshop has classes and equipment for reasonable prices:
2nd this - I took the molding class, and it's surprisingly easy to use. The real issue is that moldmaking is hard. The Tormach is a small piece. Still though - crazy that small scale injection molding is that accessible.
3d Printing is better suited for prototyping and Injection molding is where you take it once you need a bunch of parts made because a 3d print can take minutes/hours, while an injection molded part takes seconds.
Weird timestamp on some of the pictures: DD/MM/YYYY?
The image management by the molder is interesting: they're named Western Tool and Mold, and make a big deal about being run by an American; but of course they're based in Hong Kong.
DD/MM/YYYY is the most common date format across the world. You can't seriously expect that because one American is involved that the a whole company (who will work with suppliers and end users of any numbers in any number of places) will work on the date format of the country he grew up in.
I loved polymer technology classes and labs at university. It's an incredibly fascinating domain. If I have I stayed in mechanical engineering, I would have definitely specialised in polymers.
Injection Molder: http://techshop.ws/class_signup.html?a=1&i=43224759
Tormach CNC Mill: http://techshop.ws/class_signup.html?a=1&i=43094304