Design Notes:inspired by http://www.thingiverse.com/thing:126716(thanks to mooncactus!)---Advantages over the original:- No drilling needed!- More stable rail profile- Compatible with "motor corner"- The spring fixes the screw but allows to easily adjust it without too much resistance.---Print Setup:I recommend about 25% infill, 0.8mm wall thickness and  0.15mm layer height.---Assembly:Take the screw and nut from the toggle fixing and insert the nut into the slider. Insert the slider into the main part (there are two different sides! place it the way that the marking "B" is facing the wooden back panel). Now place the holdfast in the main part and fix it with 10mm screws from the left and right. Take the M3 toggle fixing screw and glue the little thumbwheel on it. Remove the thread on the upper part where the spring goes (otherwise the spring will maybe scratch on the thread). Place the spring (out of a eletrical lighter or ballpen) on it - optional! you can also use a M3 nut, which you glue to the screw - and insert the screw (through the holes in the main part, the slider and the holdfast). Push the screw downwards until there is enough tension in the spring and fix it with an nylon lock nut at the bottom.Place the whole thing on the backside of your ultimaker and tighten it with an 12-16mm screw (or two) from the inside. Place a cardboard between the z-endstop and the back panel in order to get some distance between the endstop and the wood. Tighten the endstop with 25mm screws (just a bit!). Remove the cardboard afterwards.