Be warned - The only metalworking note here involves HSS steel jigsaw blades ... other than that, I hope some people benefit/improve on the idea or at least have some fun:
Last year we bought one of those little Halloween pumpkin carving sets and in it was a little saw-type tool that was pretty nifty and broke by the end of the night. This year, I experimented and came up with a use for old/cheap jigsaw blades and hope maybe it will help you have some fun with your kids.
I have a bunch of cheap 8, 10 and 12TPI HSS blades that I got in a bulk pack with one of my Harbor Freight orders. Totally unremarkable Chinese bulk stuff . What I did was dig around and found some 1/2" hardwood dowel tucked in the corner of my shop. I then cut off some
2" lengths and sanded a bevel on all of the edges, put each dowel in a vise such that I could run up the middle with my jig saw (using a real Lennox blade :-) and make a 1/2 to 3/4" groove to hold the cheap blade. I then epoxied the blades in place. The experiement worked fairly well and we carved the pumpkins we bought for the kids.Recommendations - epoxy them the day before & not the night of carving! Also, use tape or something to really hold the wood tight against the blade. My epoxy either wasn't fully set or I didn't use enough as the blades loosened up on 3 of the 4 cutters I made. If I had time and the forethought, I might have drilled the handle and run either a rivet or small bolt through the hole of the jigsaw into a countersunk hole and really secured the blade. That might have even worked without needing epoxy.
Last suggestion, use bigger diameter dowels and maybe a little longer shaft. The 1/2"x2" I made just wasn't enough to hold on to with my big hands.
Hope this give you some ideas.
--George