I created a slider that should work for you. There are 2 STL files & 1 openscad file with the names:
Since I have not tested these, if you need to change the size of M6 holes, the variables to change in the openscad file are:
M6 = 6.5; //M6 Hole Diameter
M6Head = 11.5; //M6 Head Diameter (10mm for M5),11.5mm for M6
M6_res = 28; //Resolution of M6 Bolt
M6Head_Res = 52; //Resolution of M6 Countersunk Heads
I did not get around to updating the carriage design yet.
Here is the link to that newer version again. http://www.thingiverse.com/thing:1793640