The stock Hobie tiller extension is $80.

I used a piece of 3/4" EMT conduit for the first year I had my H16. I just glued a dirtbike grip on for the end. For where it mounts to the tiller x-bar I just flattened it out a little bit and drilled a hole through for the pin. I also had to grind the end so it was round and would clear the hinge yoke. Spray painted it black and it worked well enough.

It was heavy!! but worked.