Customized version of https://www.thingiverse.com/thing:21112

Created with Customizer! https://www.thingiverse.com/apps/customizer/run?thing_id=21112

Using the following options:

holeaccess = Flange
$fn = 80
smallsize = 80
largesize = 92
smallflange = 3
largeflange = 4
wallthickness = 2
cowlingheight = 30
smallholes = 71.5
largeholes = 105
smallholesize = 4.5
largeholesize = 4.5