Reinforced Blower/Radial Fan Duct (Tevo Tarantula)

A reinforced version of the original duct (http://www.thingiverse.com/thing:1850163) by supasorn, made after mine broke while I was installing the fans.

Changes:
- Thickened outer wall of ducts from ~0.5mm to ~1.5mm
- Thickened main brace by 2mm (requires longer screws, or using the (~~untested~~) inset screw model)
- Added and modified fillets in several places to increase part strength

All internal dimensions are the same, but it's much sturdier and has a lot less flex. It should work