sn04 mount and slider

This is a remix of https://www.thingiverse.com/thing:2254785
I could not get the original to fit on my system, so I made this one which uses the original proximity sensor plate screw holes. After installing it i noticed that the back plate is too thick and hits to the frame before it hits x endstop. It's just few millimeter away. I fixed it with a thin copper wire which hits the endstop before the extruder assembly hit the frame. Alternatively you can make the back plate thinner to 3 mm and it