AQUARIUM SLATE ?

Like BK said, if you just strike the slate it will break every which way. I have had good success guiding it by tapping along the line I want the break to follow but not hitting it hard enough to break it and going back over the line several times until it finally breaks. Its like each time I tap it, the slate gets slightly weaker in that spot and as I go over and over the line it finally weakens enough to break. Not a precision cut but a good approximation of where I was guiding it. If I wanted a precision cut, I'd use a tile cutting saw but who would want something with those smooth edges in a tank. It would be like getting precut shapes and just sticking them together. Easier but not a natural rock look at all.
 
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