Aww yeah, I'm back at it with the coroplast. I could not believe how cheap it was here in the USA. One 4' x 8' sheet cost only $15 US.
I used half the sheet at the back of the car. In stock configuration the ZE2 Insight is already pretty well covered at the front.
Click here for a higher resolution version of the picture where you can read my measurements in case you want to make your own.
There are two plastic trim clips and two black screws holding on the bumper cover at the back. This panel slides underneath the bumper cover lip and is affixed by those screws. I also put some extra screws, 2 on each side, into the plastic trim behind the wheel wells. You can see those on the left and right. Then up front I put 4 screws into a plastic piece that hangs down. Those ones have black washers, which is why they can be seen in this photo.
There are two cut-outs for the exhaust. The funny diagonal one might not be like totally necessary, but eventually the muffler would have worn a hole there anyway, so it seemed prudent to make a cut-out.
*EDIT*
Oh I almost forgot, yesterday I took out the partial radiator block. It was warm last night and I had the A/C running (because I was driving for Uber and Lyft, as a faithful hypermiler I would NEVER run the A/C in a situation where I could have just used a tank-top + shorts + sandals) and I saw the water temp at 86°C and heard the cooling fan come on. But if it gets cold again (because global warming isn't real, right guys?</sarcasm>) then it'll go back in.