I was unable to source a regular y-carriage for a reasonable price for my Prusa i3 so I designed a y-carriage which can be printed on a 200x200 printbed. Can use three or four LM8UU bearings.Designed to use i3 alu bearing holder designed by richard_j_m which is available on Thingiverse:http://www.thingiverse.com/thing:64688I also made larger arms so it can be used with a 300x200mm heated bed as I am using now.