use some m3 nuts and screws, length depends on the length of your fans. Alternatively you can use zip ties.I prefer to mount the fans under the part2, but you can also put the fans on top of the part2.
The native Inventor files are fully parametric and can be opened and manipulated in any version of the software that is 2010 or newer. The feature trees and parameter tables are logically arranged and clearly labeled, making edits a breeze. All gears have been exported as STP files, allowing them to be opened in any 3D CAD software and many 3D graphics applications. All gears have also been exported as STL files, making them ready for 3D printing.
Those parts allow you too increase the space between the bottom plates. You can hide ESCs (better stability and reactivity due to less inertia on arms) and a nice front (and bottom if you want) light based on LED strip.
UNTESTED :D but it should work. It has 2 positions one for 9.4mm distance, and other for 8.4mm distance if you use the I2K. I'll change this after testing it, but it should just work. Ofc I plan to change the little triangles alignment, but for now it works for me. I highly recommend you use the Anders Olsson adjustable spacer: https://www.youmagine.com/designs/um2-adjustable-spring-replacement  https://www.youmagine.com/designs/um2-adjustable-spring-replacement
I lost a couple height-setting spacers one day when the nut that holds them came loose and the bolt dropped out. Rather than pay for new ones, I slapped this together. They hold up for around 1 season of mowing (7 or 8 months) before they break down enough to require replacing. Adding a fender washer to the top (and even bottom) would drastically improve their lifespan. See time-lapses of the things I print here: https://www.youtube.com/channel/UCQ9nW8XQAPWKGGKRd9LFQNQ  https://www.youtube.com/channel/UCQ9nW8XQAPWKGGKRd9LFQNQ