The idea was to first have a fully printed object. Secondly, a mechanism that would permit to higher the strenght by pre-compressing the spring. It was initially destinated to participate to the contest, but I couldn't finish it in time, unfortunately.

The main body is a print in place object combining two elements. The assembly is easy, as long as your printer is well calibrated. The clearance of the rotating screw is of 0.4 mm. You'll also need to cut a little piece of filament long by around 15 mm to link the cam with the spring (like in the video). 

Recommended settings for a Ø 0.4 mm nozzle :

• Layer height : 0.25 mm
• Wall lines : 3 (1.2 mm)
• Infill line width : 0.6 mm
• Infill density : 15-20%
• Speed : 40 mm/s average

The button and the cam should give better sliding results at thinner layer heights, like 0.15 mm. The spring will print better with a line width of 0.6 mm (even with a regular nozzle).