While stirring, slowly pour the borax solution into the glue solution. Try to pour the borax solution all around the plastic cup, and leave any undissolved particles of borax in the small container. You may need to squeeze the slime with your hands to make sure it’s well mixed. You may want to scoop the slime onto a plate so it’s easier to knead. Remember to keep your slime away from the carpet and furniture! Storing it in a sealed plastic bag will prolong its use.