I designed this in blender as an orthocopter stlye drive mechanism for a butterfly project i am working on.
A linear movement on the "Ball" string causes mirrored rotational movement on connected arms.
Print 2 Cogs,2 arms,2 pins
1 support bracket
0.1mm or better layer height (thats is if you want small mech.)
The Ball chain shown needs support to baseplate whilst printing .... NB:- Make sure the first layer is a good one (or a ball may shoot of the print table....trust me on this one)
Press fit the pieces together (they are designed as interference fit)
Work the peices back and forth until they glide... it takes a while .. this will result in a gear system with less back-lash.