Replying to Need Some Help With A Box

So today, my friends and I were hitting a box that we made. Its just plywood with 2x4's inside for support and plexiglass covering the time. After a while, the plexiglass started to crack. Then my friend who snowboards pretty much ate shit hard on it and chipped a huge section out of the plexiglass. I'm kind of wondering if there is any better material to use on the top, or a different technique to it. Not sure, just looking for some ideas and help. +K as well.