Hi all. My first post here. I have a friend that knows I am a fish addict and so he gave me some acrylic he had sitting around his garage for years now. Only enough to maybe get four sides. It's 1/2 thick but has some scratches and such. My question is. How thick would the bottom need to be if it's sitting on a flat surface? Any good step by step instructional videos? Can I polish out the scratches? Thanks all and it's great being here!