This is an easy-to-make algae scraper for scraping algae (duh) off of glass aquarium walls. Not recommended for acrylic tanks, as it may scratch the walls.
Note: This is not my idea. The original idea came from Here
Note: Hot glue guns get hot. razor blades are sharp. any injuries you may obtain while making this instructable is not my fault.

Step 1: Gather Tools/Materials

The tools and materials are as follows:
1- Razor blade
2- Pens with caps (Preferably the same brand/type)
1- Hot glue gun w/glue
1- Cutting Tool

Step 2: Take Apart Pens.

First, plug in the hot glue gun. Then, take apart the pens so that they are just two empty tubes. DO NOT THROW AWAY CAPS. We will need one of them later on.

Step 3: Prep. the Cap, and Attach Pens.

You're gonna wanna use the cutting tool of your choice to cut one end of the cap, so its got two openings. Then you need to cut off the long part that sticks out the bottom. To connect the pen tubes, I put one pen halfway thru one end of the cap, and hot glue it. When it is cooled, I do the other pen.

Step 4: Glue the Blade On.

Hot glue the razor blade on one end of the pens, at a 45 degree angle. See second picture.
(srry for bad pics.)

Step 5: The Finished Product.

To use,hold the handle (pens) vertical and scrape off the aglgae. Time for some major algae-butt kicking!
Note: I know the pictures aren't that great, so please don't complain, unless you have some advice to give me on how to take better pictures. thanx :)