University of Virginia
Music Paper
Composing your own music is just a click away with this blank music paper. Several templates are available to help you quickly begin composing. Simply select the one you would like and print out as many copies as you need.
Other
Music Sheaf: Music Paper
Here is an excellent site that allows you to print your own music paper. The great feature of this site is that you can also create your own customized version of music paper to better suit your needs.
OpenStax
Open Stax: Catherine Schmidt Jones: Scoring Music: Write for Specific Instruments
If you are interested in arranging your own music, you should check out the tips offered at this website. Including a history of how music was arranged, this site also gives several good ideas of how to make your arrangements interesting.
PBS
Pbs: Caillou's Magic Keyboard
This site allows young children to explore composition using elements supplied by the program, to create short, original musical pieces. The instructions are read aloud.