I was browsing through some old pictures and stumbled across several interesting ones. These show using Goop to make hinges on my Multiplex Parkmaster. The date on the pics is June 2013. The control surface is beveled and held together with sand bags. First the Goop was applied, then I used a popsicle stick sanded to a point to remove the excess Goop. The hinges worked well. Can’t imagine why this technique wouldn’t work with foam board. More tips for foam board model builders on my blog here: https://foamboardflyers.com/.