Modeled a Nerf Rapidstrike 180 motor cover with viewing windows, this is the followup, which I model the flywheel side cover, it also contain design which let you have a place to house LED lights.
The other interchangeable designs will be maintain at the Nerf Rapidstrike 180 Motor Cover:
https://www.thingiverse.com/thing:2732163
I used the free software "designspark mechanical" to do these and had included the source files for the model, those file with extension ".rsdoc".