I love my Makerfarm Prusa i3, but the laser-cut endstop holder for the Y-axis wasn't long enough to put the endstop where I needed it, so I made my own. Enjoy!
*** UPDATE ***
It appears that newer i3 kits from Makerfarm have a new-and-improved end stop holder for the Y-axis. This part may not be necessary if you have a more recent kit.