Very simple. Theoreticly. lol
But, it takes a little practice to get the bottom piece cut to match the top. Under and over cutting are the challenge unless your blade is perfectly square to the saw table. I suggest trying 2 or 3 layers first. I can stack 6 quarter inch layers...but it took a good bit of practice.
Say your pattern fits nicely on a 12"x12" piece of wood. But, it has 300 inside cuts and you would like one for Mom and Aunt Betty and you dont want to cut 900 inside cuts.
After you place your pattern on the top piece and stacked your other layers of wood, clamp it together ..tape works too. Be sure the wood grain direction is what you like, I've overlooked that a few times and now I have to re-cut a bunch of stuff because the grain direction is the wrong way...
Keeping things nice and square is the key to the whole process.
Now, in a few of the larger inside cuts of your pattern (usually one in every corner and a few in the middle) drill some small holes for finish nails, be sure the holes are not wider than the nail and make sure you drill the holes nice and square (straight), because you will be sawing around them eventually. Nail them together, but be sure they dont stick out the bottom, naturally, its ok if they stick out the top as long as they clear the top blade clamp. Now you should have a chunk of wood.
Now your ready to drill all the blade entry holes and start cutting all the inside cuts, leaving the nails in place untill last. If your doing a piece that has an outside profile, like the one I have shown, I like to do that first...but its a matter of preference, Just as long as you keep the stack fastened till the end. When cutting the last nail out, I like to secure the stack with a few pieces of masking tape to ensure the stack doesn't pivot on the last nail.
Once you cut the last nail out and unfold your stack, It's like magic!
I hope this is clear and if you have any questions feel free to ask!
Chris