Dry Cell Case Material?

I am rebuilding my old dry cell. I had used clear acrylic case material but I ran into a problem where it was kind of thin and would sometimes crack. I do like being able to see the through the material although i realize that is not really necessary. My question is where have folks been able to find thick acrylic or something clear to use for a casing material? For example when I looked before I was only able to find 1/4 inch thick material from home depot. Is there a better source?