Reciprocating rack.

thingiverse

A 3D printed version of mechanism #123 in 507 movements.http://507movements.com/index13.html A video of it in action is here: http://youtu.be/dfs8X2RW-1k And an animation of the action is here: https://youtu.be/Wq4kBHMocGU Printed in Diamond Age PLA on an Ultimaker 1. Designed in MOI. The longest piece is the rack which is 241mm long. Probably too long for some machines so I've included an alternative design in which the rack is spit into 2 (rack 03 u and rack 03 l) held together with two rack clamps and 8-off M3 x 10lg button head cap screws. If you can get away with the single piece rack (scaling down might work, I haven't tried it) then only 8-off M3 x 10lg button head cap screws are required (rather than a total of 16, that is). Disadvantages of scalling down more that a small amount are: Holes for the screws will be small Parts that are a tap fit might become too tight and require individual scaling. Instructions I made the parts in Diamond Age PLA on an Ultimaker 1. I used 1.2mm wall thickness all around and 20% fill and a temperature of 210C. You may have to alter the part orientation prior to printing. The sides of gears that have been in contact with the print plate will need to be trimmed of excess material. Similarly for parts that are a tap fit together: gear hubs in the base; handle parts. The handle parts are a pretty tight fit. If too tight I suggest scaling the handle link up a bit.