I printed this on a Printrbot+ with 3 mm. ABS. It's not the easiest thing in the world to print because of the two tall towers. I recommend using no cooling on the base, and then cool the heck out of the towers. Print slower than normal too. Also, a brim will help keep this thing from coming loose.

I tried printing this with Makergeeks' eco-Flex PLA and it was an epic fail. That stuff is so flexible, the plugs printed as spirals becasue they twisted under the circular motion of the extruder putting down each new layer.