On Monday, January 7, 2019 at 1:27:14 PM UTC-8, wrote:
Steve Bralla manufactured the "Z5" eccentric tool for several years before losing access to the machine tools needed for fabricating them. He kindly offered the rights to me a couple of years ago. I have been building them since then, and although they are not on my website (yet), I am still making and stocking them.

info (at) mmfabrication (dot) com

I've got one of the Z5 eccentric tools, and its a great help. But it can only be inserted when the wings are within about ¼" from closure. It would be even better if more eccentricity was present, to allow the tool to be inserted with the wings further from closure. I think the strength of the plastic tool could be maintained by putting a steel rod down the center.