scrapers

What’s the cheapest macgyver type algae scrubber that I can put together using household items? I don’t have any clean scotchbrite or anything like that… but I do have double sided razor blades and old t shirts.. Bonus points for pictures, I’m a visual learner.

I've recently been given a couple of algae scrapers. They are very simple; just a long handle with a plastic rectangular head that you pull off (from between two holding-prongs) so that you can change the blade inside. The blade would be sandwiched between the two bits of plastic and all held...