I have no idea, but I'll be interested in learning, too! We'll be making a beanbag-toss game out of plywood for our church fair next fall :-).
Get somebody who knows what they are doing to cut it. Remember: Safety First.
Not much of a tool guy, hey, Rudy??
Don't need a sawhorse. If your front (or back) porch is flat and of the appropriate size, just lay it flat with the part to be cut hanging over the side. Kneel on the sheet and cut. You will have to make several adjustments during the process but it will work.
This isn't a very dangerous job. Hell, I'd just lift the thing off of the garage floor with bricks or blocks and cut away. The weight of the plywood is such that it won't move much, and you can stabilize it with your leg.
In all seriousness, let someone with some experience do it. You need to support the scrap during the cut. Use the right kind of blade (a sharp one) in the saw and don't rush the cut by pushing too hard.
Rent or buy a really good quality (like Bosch) and buy some extra blades, since you will probably break a few.
Support it on some 2 x 4's ( or thicker). Be sure the blade isn't hitting the support Sawhorses are easier for your back. Have a helper support the drop off. Have the supports close to the cut to lessen vibration. Test your cutting tool handling on scrap before you start on the good sheet.
Or just have a milling or cabinet shope cut it for you.
Don't try to do this without the proper tools and staging equipment.
If you have a neighbor or janitor who has a workshop, take the project
to them.
Power Tools and Power (ful) tools like saws and knives are dangerous.
Wear goggles and use gloves.
-- Rejoicing Jo --
No problem here Rudy. Use your deck or a couple of 2 x 4's in the garage. Just don't try to cut out the entire silhouette without cutting off the scarp at intervals and you'll do just fine.
Get a grip people!
This is really a simple job. You won't need the ear plugs, the glasses may keep sawdust out of your eyes, the really careful would say use a mask to prevent inhaling any sawdust, but for God's sake...people have been doing simple projects like this forever...and surviving.
Sheesh!
If you don't do this, then the unsupported secion will sag as it's being cut loose, which results in binding the saw blade and then all manner of unpleasant things tend to follow.
Use two sheets of plywood, on a flat surface. Draw your picture/pattern on the top sheet. The bottowm sheet might get scarred, but bettter it than your front porch or table. Set the depth of your router to the depth of 1 sheet of plywood. Using a cutoff bit plunge it into the sheet of plywood on the outside of your pattern and then follow the pattern you have drawn. Pull the router don't push. Use a steady slow motion.
Always use saftey. Don't let the router get away from you.