Marble pumps have been around for years and, most often, are made of wood. I've made quite a few out of wood, but each time it required "whittling" to make it work. With a 3D printer, no whittling is required (well, except for a few stray strands in the arches).
The photo and video show the marble pump motorized, but the motor is not required as the crankshaft can easily be spun by hand (maybe someone will add a handle?).
Printed in PLA using Makerware 126.96.36.199 ("Standard" settings) and a Replicator 2.
This assembly is a test for a larger project.
1) "Someone" (me) added a handle and a minimized base. Vrack requested a handle for the non-motorized version of Marble Pump. The files "Handle.stl" and "Base No Motor.stl" have been added as requested. Haven't tested them yet.
1) "6VDC 45 RPM Pinky Finger Sized Gear Motor 1" Long x 15/32" x 3/8"" from either amazon.com or directly from http://sciplus.com/p/MICROMOTOR_47952. Other sources are available, I've not tested them though.
2) Coaxial Power Jack - Radio Shack part number 274-1583.
3) 3 Vdc Power Supply - Radio Shack part number 273-315.
4) 22 gauge wire.
"Slide.stl", "Journal Crankshaft.stl", and "Crankshaft.stl" can be a little little tricky to assemble inside "Housing.stl".