My husband, being a guy, would not even consider wearing my Valentine Gears Pin http://www.thingiverse.com/thing:410984, so I redesigned the pin to desktop size, altering its mechanism so that the upper right gear now has a little knob for turning and the frame goes all around the heart. It's as big as I can make on my printer's plate, so about 4" (100 mm) square. The photo is my "draft" copy - which worked as soon as I snapped on the gears. I'm so excited! Yeah! I made a movie on my iPhone, but I don't have the right file type to upload it - yet. I hope to make a much better looking one for my husband ASAP and will post a photo of it. I hope somebody does this with a better use of color than mine - please share a photo when you do!
YouTube video: http://youtu.be/0YQyrHCpOKY
UPDATE: I haven't had any trouble myself with the handle on the gear at the upper right of the heart, but I noticed in a recent print that it can come out really skinny. I liked the somewhat delicate shape, but thought it might be wiser to go with sturdy. So, I'm adding a plate for the gears that incorporates this sturdier handle.
I printed using 0.3 mm layers and 3 shells with 20% infill.