How to make sugar glass without corn syrup or cream of tartar?

I'm trying to make a relief sculpture copy out of sugar glass. I don't live in the US, so the corn syrup is not easily available. I read in multiple recipes that cream of tartar can be substituted with any edible acid, like citric acid.

I'd like to know more about the chemistry behind the ingredients, and find edible substitutes. Additionally, how can I make sure that it doesn't lose transparency and go brown? And what about preventing it from cracking too soon?