Print with 0.2 mm layer heights--the inflill percent doesn't matter. All of the designs have the common parts in common: - 3 M3 nuts - 1 spring: http://www.mcmaster.com/#9657K51 For 8 mm wide: - 2 M3 x 8 screws - 1 M3 x 6 screw For 12 mm wide: - 2 M3 x 12 - 1 M3 x 10 For 16 mm wide - 2 M3 x 16 - 1 M3 x 14 For 24 mm wide -2 M3 x 20 -1 M3 x 18 Use a shorter M3 screw and nut to connect the inner two parts. You'll want to leave them loose for now. Then assemble and use two long M3 screws and nuts to hold the entire assembly together. Once you've assembled all four pieces, pull the inner parts so both are touching the top and then tighten the shorter screw. Finally, insert the spring as shown in the photograph.