I have been searching for new shin pads for soccer for a while. Most that are on the shelves here are thick and and awkward. I finally got some anyway (Nike Mercurial Lite), but hated them because they were way too wide in the bottom.
Then someone mentioned that hers were intended to be heat molded. I figured the chances of mine being a thermoplastic were pretty good. So, I put them into a pot of boiling water for about a minute and pushed them into shape over a pair of socks. They molded quite easily. Wrapped a velcro strap around them while they cooled down, and they now seem to hold their shape nicely.
The finish that used to be shiny on the outside is now a bit wrinkly; this may actually be a good thing, maybe it will make them less slippery.
Will have to see if they last and keep their shape.