I am looking to purchase a new contact frame, 20x24 in size. I am considering a large piece of glass, but is taking time to source.

So the two companies that I know of selling contact frames, Bostick and Sullivan and the Photographer's Formulary. I have a B&S contact frame and it appears that I may have to re-glue the miter joints which are starting to separate, it shouldnt as its not that old. Has anyone used a contact frame from the photographer's formulary? If I have to make one, I'm probably better off trying to find plate glass, time has somehow turned into a commodity that keeps slipping away.

Thanks for any ideas or tips