whats best for glass

When it comes right down to it theres nothing that looks more like glass than ... Glass !

Try using the  glass slip covers that you find with a microscope.

you can get them from Scientific American Supply

Now cutting glass to the right size........

thank you all for your help

You can also buy clear acetate at many hobby shops- may be a bit cheaper than clear styene, will work just as well.

Clear acetate sheets used for overhead projectors. (a rapidly vanishing presentation tool).

The clear plastic "report covers" you may remember from high school. These come in a variety of colors.

These are thinner than sheet styrene which may be a disadvantage or advantage.

I confiscated a huge box of no longer used hands-on counting/math tools teachers in our math department trashed when the state decided such tools were no longer effective. It contained clear plastic circles, rectangles, triangles in many colors and sizes. I've used these on several projects.

The clear stuff on product packaging makes great model glass. And it's free.

I'll echo Glenn. You can buy sheets of clear styrene, I have used these in the past for windows.

Sounds like clear plastic sheets are in order. They're available at any lhs or online store.

Glenn