I love that the hamburger is made of corduroy! A great way to branch out would be to make pizza with re-arrangeable toppings. I can see little kids flipping out over toys like that. Hell, I flip out over toys like that.
I suppose that you could make something out of the plastic tubing that you find in hardware stores. You could make rings out of it, and chain them together, or else have one big ring with smaller rings attached to it (think like a key chain). Because the tubing is hollow you could thread things inside of it (beads, ribbon, etc) to make it more colourful (The tubing that I'm thinking of is clear) That way you'd have something that was almost a teething ring that could also be sterilized..... however, not having ever tried it myself, I can't say that it would work. And I don't know how you'd attach the two ends of the tubes when you're making them into circles (I guess you could try melting them together?)
just an idea that randomly popped into my head.....
In Canada it's totally illegal to deface coins (ie. punch holes in them). When I was a kid I used to hammer holes though pennies to make necklaces, and I got in trouble. Not the "being taken to court at age 13" kind of trouble, but moreso, the "you better stop doing that proto" kind of trouble. However, there are different currencies that already have holes, which you could look into at coin shops (for coin collectors). Some you can find for pretty cheep as they aren't collectors items. Also try hitting up your friends who travel.
I used to dumpster photos from a photography studio near my house, and as a result made many fun crafts from repetitive, slightly damaged prints. My favorite thing to do is to make envelopes from them. If you overlap the edges, you can sew the different images together, forming a cross between a quilt and a collage. The paper is thick enough that it doesn't tear. I liked to layer the same image over and over (like the left side of a bride's face) or cut landscapes in to 2" squares and mix and match. My penpals loved it.