AnyCubic i3 Dial Gauge Holder

Remix of https://www.thingiverse.com/thing:1445744 to fit AnyCubic i3 Mega printer and Neoteck NTK021 gauge.

- Adjusted spacing for 8mm rails spaced 50mm on center.
- Moved the hole for the gauge mount higher as my gauge bottom's out with the original location and my Z axis homed.
- Adjusted slot for mounting bracket to fit Neoteck - 16mm X 9mm with bolt hole 12mm from the gauge