A hand cranked version of this thing: http://www.thingiverse.com/thing:324023.
Video of prototype is here: https://www.youtube.com/watch?v=vYGLG5_vWZQ.
Thingiverse citizen alexlfarlow asked for a hand cranked version, so here it is.
Print the parts then assemble as per "Assembly.skp".
Test fit all parts before final assembly. The cams should fit on the axle very tight, the cams with bushings should rotate freely on the base arms, and the ripples should move smoothly in "Guide.stl".
Once completely assembled and tested, a little thick cyanoacrylate will assist in holding the cams and crank in place.
Install the cams on the axle, noting carefully the type, position and orientation of each cam on the axle. Once completed, insert the cam with the longest bushing into the arm on "Base.stl" that is closest to the guide pin. Lubricate the cam surfaces with white lithium grease.
Press "Guide.stl" into "Guide Tube.stl" aligning the guide pin in "Guide Tube.stl" with the slot in "Guide.stl". Lubricate the guide holes with light machine oil.
Slide the guide tube assembly over the base assembly, again noting the position of the guide pin and making sure the longest bushing extends through the guide tube.
Press "Knob.stl" into "Crank.stl".
Press the crank assembly into the longest bushing.
Place the ripples into the slots in "Guide.stl", carefully noting the orientation of the angles on the ripple arms.
Turn the crank clockwise, and ripple on.