Sculpt with modeling clay. Have the child roll the clay into balls while his hands are placed in a clap position and his fingers are curled toward his palms. This strengthens his muscles. Ask him to make "green peas" with his fingertips to isolate finger movements, or provide him with a plastic knife or an old pair of scissors to cut through the dough.
Teach your child to play "newspaper basketball." Not only will does this appeal to a child's innate joy in throwing objects, but asking him to use one hand to scrunch sheets of newspaper into a tight ball increases fine motor control as well. Alternatively, you can ask him to scrunch tissue paper into balls and glue them onto construction paper to make colorful mosaics.
Designate your child as a household helper. Put her in charge of using a spray bottle to water plants or to clean mirrors and counter tops. Pulling the spray-bottle trigger is a great muscle strengthener.
Provide your child with a pair of safety scissors and a pile of your junk mail. He can practice cutting out letters, pictures or just making straight or zigzag cuts. He can use the same scissors to fringe white or colored paper as a way to practice the control required to make partial cuts in paper.
Invest in tweezers and eyedroppers. Both items put a child's small finger muscles to task and lend themselves easily to fun games. You can have a "race" during which you see who can pick up the most cotton balls with a tweezers, or you can mix drops of colored water to create a lesson on color combinations.