I was watching some youtube videos of the green machine scapeing some tanks. I saw that they used thin black "things" as a substrate divider. Does anyone know what these are and where I could buy some? Or what does everyone use as substrate dividers?
We don't inherit this world from our parents, we borrow it from our children.
It comes in various sizes from about 2'x2' up to 4'x4'. I bought the 32"x44" size mostly or just what ever was on sale. you don't need thickness over .080" in most cases that's just adding expense for thickness you don't have to have.
You'll need a good sharp box knife and something to use as a straight edge (if you need it straight).
I usually plan out my sizes before buying then go to town to get everything at once.