wrinkled vinyl on old style cases (AES)

I have a Ninja Combat AES cart I bought brand new and it seems to have a good degree of rippling/wrinkling in the plastic vinyl. I believe tihs is called "heat warping" but I'm not sure.

Either way, is there some way to flatten out or reduce the wrinkling a bit?

Try putting the case in the freezer for an hour or so. Big Bear mentioned this tip or one similar to it a while back.

I'm going to tell you right now,if you decide to do it, don't leave it in that freezer too long at all becasue during my experimenting I found that the case will start picking up moisture and because your case is basically made out of cardboard and vinyl you don't want to ruin the cardboard.
The freezer method is not going to remove 100% either
If you are worried about the insert getting damaged by the wrinkles,I would suggest you grab a piece of 11x17 typing paper and size it to fit in your case and then place your insert over tiop of it.
-BB

I see. Is it best to wrap the case tightly with some plastic wrap or just place it in the freezer directly as-is?