I have had great success with a product called stick fast. It’s a 2 part adhesive. 1 part ca adhesive the other part is an activator. Just beware that once the 2 parts have met it’s a matter of seconds before it sets so have everything you don’t want stuck away. I wear rubber hospital gloves as I had to learn that lesson the hard way. Lol. I have used it to glue back together the main cross piece and the styrofoam. No melting no nothing but holding everything together and quickly at that