I used racers plastic. the same I used on my dirt stock cars. It is like 1/8" thick. You can get it from any oval track race supply shop such as Speedway motors.
I made paper templates then transferred the pattern to the plastic, You just heavily score the plastic with a exacto knife, razor blade, etc and snap the plastic at the "score" Sometimes it snaps clean and sometimes you have to finish the cut after the snap. I just ziptied the panels to the cage. I didnt want to drill a bunch of holes in the cage for rivets. I intend on redoing the paanels with red panels when I fabricate the fron fenders (area). I wll have a windshield on it before winter and I am going to enclose the engine area partially to protect from mud and water splash. also going to duct and snorkle air in to the motor where needed and prety much waterproof the engine and electronics.
I forgot about the cam, that is in the near future also. We do mud, trail riding with alot of hilly terrain, That is why the clutch weight/spring combination I chose. Need to shoot up hills and power through the mud.
Here is a video of the grand kids boggin. before the clutch work.