Pretzel dough would be great....like those big soft pretzels...I will see if I can find you a recipe...but I bet you could easily find one online. Also ginger bread..but it is actually pretty hard to work with. I had such trouble baking and working with it myself (and I can bake!) that I finally went out and bought pre-made houses...at Christmas time.
There are these cool cookies called stained glass cookies....you could study stained glass..then they could make their own stained glass cookies. You just use a stiff sugar cookie recipe (I have one that you don't have to refrigerate) and then roll the dough into coils and make shapes that are open in the middle. Then you fill the middle with crush hard candy...you have to watch it because the sugar will burn. Also make sure you use parchment paper underneath.
They are my favorite kind of cookie...I learned to make them from one of my teachers in the 6th grade!