Wahl Designer Clipper Guard, 1.5", 1.75", 2", 2.5", and 3"

I made some adjustments to rmeyers's 1.5" custom guard:
- Scaled the model to millimeters.
- Reoriented the model so it sits the way I print it (see below).
- Changed where the tabs and sides are so it fits my clippers (Wahl Designer).
- Thickened and reinforced several areas of the model.
- Rounded the tips so they're not so sharp and stabby.
- Added 2.5" and 3" versions, by request. Note that THESE TWO SIZES ARE UNTESTED. Please let me know if they work for you, so I can update this te