if you cut hanger wire at a sharp angle you have a stepped scraping tool. it scratches sometimes, but removes coralline algae thoroughly!
also this, a razor blade and surgical tools
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and this one, I can slip a piece of scouring pad for dish washing, a little cut disk, in between the miniature scraper I built it will cut microalgae on the glass which is harder than coralline algae to remove
I have to build many miniature tools to work with palmtop reef