Just in time for Valentine's day; this is a slight modification to the thumb driven heart gear box that eliminates the thumb gear and adds a directly driven center piece that is turned by twisting the base.
Updates
02/10/2015: Uploaded corrected sleeve stl file. This one is taller to reduce the gap, thanks to cfeniak for pointing this out. The original upload was a previous version and was too short for final design.
02/04/2017: Added all parts to this thing, removed differential crank since the direct drive seems to be working fine after testing. Split lid and base of heart to allow for a cleaner look and ability to better differentiate with 2 colors (see featured photo). Print parts 01.stl through 09.stl in one color and the remaining in a second color. Updated instructions and summery.
02/05/2017: Added 1-2 gear ratio pieces (untested).