Help! Need an Emergency Halloween Craft!

Friends,

I just recieved a special request to take a group of teenagers to do a service project at our local YWCA Family Center: a housing facility for families who are temporarily in need of a home. We were asked to provide activities for the children of the families for an hour and half tomorrow afternoon.

Though the Family Center has an excellent playground (a dragon made of recycled tires, and a pirate ship!), the weather is unpredictable, so I need to plan an inside activity.

Please suggest ideas for a halloween craft (or crafts) that would appeal to kids of a variety of ages, and that uses readily available materials.

Thanks!