As Chip said, wet your surfaces with unthickened epoxy before gluing two pieces with a thickened epoxy mix. I have the West video and they make really thick mixes - like very thick peanut butter. It won't fall off a putty knife upside down. I use it this way all the time and it hardens like a rock. You'll know it when you try to sand it. Bottom line is - make it as thick as you like.