A super simple and quick one. My son is learning his ABC's, and my wife saw a plastic version of this where the child assembles the letter-shapes. So I figured out the minimum number of sticks necessary to build the entire alphabet, uppercase and lowercase, and cranked this out in 20 minutes.
It fits in a ziplock bag so we can take it with us and get it out while waiting for food or whatever. I liked it so much I made another set for my niece.