Plastic insulator for laptop hard drive (preventing short circuits onhard drive caddy)

Hi,

I need to replace a hard drive in a laptop. The hard drive is mounted
in a metal caddy. There's a brown plastic insulator glued to the metal
caddy to prevent the circuit board of the original hard drive touching
the metal and cause a short circuit. The plastic is custom-cut for the
original hard drive (the circuit board doesn't cover the entire hard
drive top surface). The new hard drive has a circuit board covering
the whole hard drive top surface. So there's an area where the circuit
board touches the metal of the caddy.

The question is : Where can we buy some plastic insulator sheets?

It doesn't seem available anywhere...

What I've used, while finding a better answer here, is a 3M Colour
Copier Transparency Film. They're supposed to be more resistant to
heat since they're made for Colour Copiers. I've cut a rectangle out
of one sheet and fitted it between the hard drive and the top of the
caddy.

What do you guys think? Any ideas of where to buy the real stuff?

3M CG5000 Dual-Purpose Transparency Film
http://tiny.cc/yqqwF

MSDS (PDF)
http://tiny.cc/4Ocs4


I've made my own tests and here are the results :

-The transparency and the original brown plastic both burn at
approximately the same pace when lighted with fire.
-I've put the transparency on a space heater. At 75 deg Celsius, the
transparency did not change in shape. At 95 deg Celcius, the
transparency curved a little bit. Typically hard drives are not
getting that hot, right? Normally they run at about 35-55 deg Celcius,
right?