One of the greatest things about the web is that people share their work, simply for the love of making things. One of the best websites for sharing CAD files is the cnc zone which has hundreds of DXF files. http://www.cnczone.com/forums/woodworking_projects/5276-dinosaur_skeleton_other_models_dxf-2.html
DXF are a 2d drawings that can be imported into any good drawing program. You don't have to have a laser cutter or CNC machine to take advantage of these files.
To get the kids started we downloaded the T-rex file and opened it up in a CAD program (pro desktop). We then scaled the drawing up so that the slots were 12mm wide, and tidied up any errors. Then printed of the drawing, full size, and true scale. This gave the kids a template to stick on their plywood and cut out with a scroll saw. They had a great time making T-rex and just as much fun making the video. Ethan (pictured) wanted one for his room, so we scaled it down to 3mms printed it out, and he spent all day cutting it out with a scroll saw , then he made a spider, and another T-rex. The whole process gets kids really engaged in making and thinking about how it was designed, and modifying designs.