I think the epoxy filler/pb is made the same as poly. Cabosil/airosil mixed in with the resin as a thickening agent. Make it as thick as you need to fit whatever application . Vertical app will need to be thick enough so it doesn't run down. Add 1/4" chopped fibers to make it more structural if needed. A little of the fibers go a long way.
Hope this helps !
