I've made about five of theses so far, very useful for reaming/milling out holes in prints when a drill is a little too much. Could also use them for taps too I guess...
Printed really well with a big brim to keep it upright and steady. All I did in the customiser was change the bit hole and left the rest as was. Have made a 3mm, 4mm, 5mm, 6mm and 8mm so far all in "tool grey" :)
Can't recall the settings now, but it was 0.2064mm layer height (imperial screw) and a high infill to keep them nice and solid. Post printing was just a little filling of the brim and poking in some M3 nuts and bolts.
Printrbot Simple Makers 1405