Learn Italian: Il bicchiere è di plastica trasparente. - The glass is made of transparent plastic.

In Italian, the preposition di is used to show what material something is made of. You do not need to add a word for "made" - saying è di (is of) is the natural and most common way to say "is made of".

I see bicchiere ends in -e. How can we tell if it is masculine or feminine?

Nouns ending in -e can be either masculine or feminine in Italian, which can be tricky! The best clue here is the word for "the" right before it: Il is a masculine article, so we know bicchiere is masculine.

Wait, doesn't bicchiere mean "glass"? Can I use it for the material glass too, like a window glass?

No, bicchiere only refers to a drinking glass. If you want to talk about the actual material glass (for example, saying something is made of glass), you would use the word vetro and say di vetro.

Why does trasparente end in -e? Shouldn't it end in -a to match the feminine word plastica?