MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
Awesome! 40mm should be perfect indoor quad. Even on 2s the 2" are still a little to quick for indoors. As a side note, if you have time it may be worth angling the 3 supports in the ducts to the opposite direction the motor spins. Can make them thinner and taller that way, which should increase strength and help with the "ducting" effect.
Example on a brushed tinywhoop frame:http://www.thingiverse.com/thing:2012458