Sort the Scraps

From the Homemade Paper site

Sort your scraps by fiber length and color, and identify the base color: the pile of scraps that most resembles the color you want the paper to be. Cut the screen Ordinary window screen works great for making paper. It should be free of dents and curves, otherwise the paper will come out in exactly the same shape. Rust-free wire screen works the best. Synthetic screen should be used with caution; it's less rigid, which can cause problems later in the process. Synthetic screen may be serviceable if used with a frame, as described below. Cut the screen the same size as the sheets you want to make, slightly large if you want to make a frame for the screen. If you intend on making lots of paper the same size you should consider building a frame around your screen. In this case allow two extra inches in each direction before cutting the screen. For example, if you want to make a frame for 8 by 10 inch paper, then cut a screen 10 by 12 inches large.

Optional

Build a frame using lengths of wood 1/2 inch wide by one inch thick, or one inch square. You don't have to get fancy, just be sure that the inside of the frame is the same size as the paper you want to make, the corners are square, and not too wobbly. Set your screen down on top of the frame evenly and nail or staple it in place. You want the screen attached snugly to the frame, without any big gaps between the wood and the screen. Blend it to bits And now a dash of paper theory--in order to make new paper from old paper, you've got to change it to a mushier state. Blenders accomplish this nicely, and the result is the pulp. Fill a blender about 3/4 full with clean water. Take a handful of scraps from your base color pile and put them into the blender. Cover the top and blend on medium-high for a few seconds. The water will start to look like very watery oatmeal.

Add various scraps one by one, and give a short blast with the blender each time. You want to put shorter fibers in first, then gradually add scraps of longer fibers. Otherwise all the fibers will end up about the same length - short!

Add any special items (including threads) last. Don't turn the blender on at this point as it may ruin these items or wreck the blender, or do both.