Okay I admit it, these letters stumped me. I did think of Yarn for the letter Y, and of course there is plenty of handmade yarn out there. The trouble is the actual craft of making yarn is called weaving.
So, after failing to come up with crafts representing these letters, I instead decided that a fun way to end the series would be to instead come up with three handmade items that quite literally represented the letters.
So here they are - the letters X, Y and Z: