Involve the neighborhood. Use the instruments you've made and create a parade through the neighborhood. With a starting point and a finish, make sure to hit the high points in town. Maybe make a banner that the little ones can carry up at the front of the line. Have a recital.
Some kids already take music lessons.
Set up an area with chairs in the backyard and have them play something familiar to all of them. Invite the neighbors for some food and a chance to see the kids perform. Make tickets and have the kids invite their friends. The young musicians are selected from a nationwide talent search. Look at From the Top to see if he or she qualifies.