Stumbled across these two links and just had to share. Make automata using recycled boxes and stuff, easy enough to do with school aged kids. The second link is better but I found it via the first.

https://sites.google.com/site/howtomakeanautomata/home/how-to-build-the-materials
http://www.exploratorium.edu/pie/downloads/Cardboard_Automata.pdf

Cool project for kids!  Heck even I could have fun making one of those.

Yeah one reason I posted it is because all the automata resources out there showcase a lot of complicated pieces. I think this is the first and only tutorial I've found actually. I was thinking of using this myself too because I'd still like to do a bit of automata if I can.

This is so cool!  I am going to make some for my granddaughter.  When I try to cut out the thick foam I had a hard time getting a nice smooth edge, but a metal cookie cutter cut it smoothly.  I saw at the cake decorating store that they had make your own cookie cutter kit the other day with strips of metals to bend. They have cookie cutter sets with concentric sized circles.  I put a board above and one on top to push it through the foam without cutting a circle in my palm. Sometimes I hit the top board with a rubber mallet.  I wonder if those electric wire cutters would work on this type foam?

A hot wire might work but I would stick with the cookie cutter. The fumes from a hot wire can be very toxic.    Clever idea with the cookie cutter by the way. It is the same concept that a factory would use to cut something like this.

Never thought of using cookie cutters, that's a great idea. You could use a sun-shaped one to create cogs.... Or is it cams?

It is similar to die cutters. My dad once made me a metal pipe piece with sharpened edges on one side with a metal file that we used to cut perfect circles from a stack of golden card stock. We put board underneath and on top and whacked it with a rubber mallet to make tons of golden coins for a treasure chest. The edges were so smooth and even a little rounded from the compression, saved us lots of time. For the foam rounds it worked but I did not try a large stack. If you whack too hard on cookie cutters they will bend eventually. I have tried to make my own cookie cutter shapes with pliers many times so I was excited to see that custom cookie cutter kit. I wonder if there is a source of decent precut foam shapes out there for another purpose that could be used for this purpose also. These projects would make very fun science class material.

Sounds like a home-made punch. What a great idea! I have been doing a little bookmaking of sorts and am using some sort of miniature awl and a hammer to make holes in the pages. I never really thought to do something similar for punching shapes, although it would be very useful for shadow puppet style stuff.

As for foam - what about craft foam? I know here there are companies that sell pre-cut foam pieces in various shapes. ... I went looking for a link and sadly my local store doesn't have a great online shop yet, but I noticed they have a pic for clay moulds (at bottom right):
http://www.spotlight.com.au/departments/craft-hobbies/kids-craft/
That could work depending on the shapes you need to make.