The Park Tool HBH-3 Extendable Handlebar Holder does not seem sturdy enough to do the job but it does!
Tightening the securing knurl is easy and the rubber holds secure. Love it.
Straps on in a split second, holds bars in position securely while you work. Allows for bars to be turned or cocked to one side for expanded versatility. Once you get this tool, you'll wonder how you ever did without it (despite the fairly substantial price.).