I made and used the standard back cover for my Jet contractors saw but thought it was a pain to have to crawl under the rear extension table to remove the cover when I was using the saw at anything but 90%. I thought about just building a box and hanging it under my extension table but I worry about the motor. I came up with an idea that is very easy to make and works surprisingly well. All you need is a piece of hardboard, a plastic bag, and some elastics or bungee.
1. Make the bezel.
Mine is 11x16.5" which fits the back of my Jet. I made it about 1" wide which just gave me enough clearance to fit it over the motor assembly.


2. Attach the bag.
I used a heavy black garbage bag for this prototype. When I make a permanent I'll try to find some wind resistant material like nylon or canvas. I just used duck tape to attach the bag but when I re-make this, I'll make another bezel and sandwich the bag between two bezels.


I then slid the bezel and bag over the motor assembly and using some Velcro I attached the bezel to the back of my saw.

I loosely gathered the bag right in front of the motor and cinched it in place with some large elastic bands. Small bungees would be great for this. Using scissors I trimmed off the excess bag leaving enough to allow me to tuck it under the elastics.

This pic shows the bag or more correctly the boot tight while the Dust Collector is running.


This view I tilted the motor to 45% Everything is still intact.


Side view...notice how the bag is gathered.


Yet another view


And one last view


So far it seems to work. I can raise, lower, and change the blade angle without messing with the back of the saw.
I'm about to start on a project to make a sofa table and I'll update you as to how well this works.