RepRapPro Mendel 3'ish X Carriage Extender

I have quite a large fan attached to my X carriage for cooling and if it's not in the correct place in terms of Z height before sending it home the fan will crash in to the side bars.

This little additional part is designed to effectively extend the x carriage so it homes a bit further out to prevent this issue.

Additionally this is required as I now home my Z using a max endstop and not a min one.