Hey Jim, who am I to make this for you, (I am flattered at the proposal) 
, I am sure you would be able to make one much better!!!! 
I would think your cost for parts would be about $10-$15. One thing I am thinking about is to have it attach to the lathe quicker instead of using a threaded rod, possibly some kind of fold over cam to pull it tight to the bed of the lathe???? I would appreciate your ideas. William
