I'm not sure if this qualifies as a craft, but it is pet related. My dog loves ice cubes and loves treats so I took some chocolate molds, put a few kibble pieces in each and filled with water. I put them in the freezer for an hour or so and now my dog Molly has a treat she'll enjoy that will keep her busy.
here is the finished product in the turtle shaped mold. i did a variety of kibble, liver treats, cheese treats and beef treats (two are missing, she tested those two)
I also did a smaller cube in a small heart that only fit 3 kibble squares, and she enjoyed those too. I would think that this would work for cats with catnip cubes. If I still had a cat I would give it a try.