Nice designs, I've seen the first around a lot but i think because almost each piece needs a void removing it is more wasteful than it needs to be. By using a simple sheet design the second design and mine makes better use of cardboard, though I have not done this to be green as I had to discard (send to be recycled) the old case.
Fire is not a practical problem but
http://www.stageservicesshop.com/sho...r-p-16134.html would be a good idea if doing this on anything more than an individual level, after all the plastic has flame retardant in. I've used this stuff for scenery and its very good.