A8 X-axis Tensioner (remix^3)

I was using my own remix of the Anet A8 X-axis tensioner rod and it failed. As seen in the photos, the part was compromised where the material was thin around the hex nut recess. This design attempts to fix this in two ways. First, extra material is added to the idler pulley fork, making it 2mm taller. Second, I've split the design into two pieces so that we don't rely on the adhesion between layers for the strength in the direction we're trying to provide tension.

Use M3 nuts in each slo