If anyone needs the tool to hold their cams when valve covers (sorry, i can't adapt to calling them head covers) are off, i have the one i created during my engine tear down. It works perfectly.
Be sure and lubricate the new O rings with proper O ring lubricant, not motor oil. Instead of the super expensive Porsche brand lubricant I used Parker Super O ring lubricant.....get a tube and you will be surprised at how often you use it in the shop. oil Changes or any time an O ring is in use