This is interesting looking stuff but a bit expensive if you ask me. It's really nothing more than a heat formable thermoplastic and the size sheets they sell it in are rather large - nearly 4' X 5' and that seems a bit awkward - especially since you can buy thermoplastic sheets in smaller sizes, easier to handle and likely less expensive or that is MORE for the same amount of money.  The key is finding a plastics place that sells thermoplastic sheeting - and there are many.  IASCO sells it in smaller sheets - likely more face sized than huge.  Cadillac Plastics company might have distributors scattered across the country that should also have it. As well some hobby and craft stores handle thermoplastic sheets (likely smaller sizes) but they all come in a variety of thicknesses .20 .30 .40 .60 are the more widely used and "standard" craft sizes used for a wide array of projects.  So look close by and then go online - there are others who have THERMOPLASTIC SHEETING (you might try Googling that) and you might find it cheaper than these folks.  It can be heated in an oven if you're doing vacuum forming OR you usually can use a heat gun and press it into molds though usually the rule of thumb with molds is "hard into soft" and/or "soft into hard" with regard to the materials used.  Trying to model a hard - even flexible but hard plastic in a plaster mold or similar usually is NOT the best method. It CAN be done but it's more trouble than going with a plastic into like a silicone mold or a flexible soft material into a hard plaster or fiberglass mold.

These folks sell smaller sheets.