Sprite Stitch Board!

I have made some really big items and they are really fragile, I have seen some people attach foam. What kind of glue would I use for that?

Assuming you've already ironed both sides to strengthen it, I believe many people use superglue for their perler projects, but that might only be for attaching perler to perler not perler to foam. I have tried using glue for my projects, but unfortunately the glue didn't really set properly, it leaked all down the perler and made it horrible, so I now use thin transparent double sided tape, which is strong enough to hold it together, but not so strong you can't pry it off and re-adjust it. Although I'm not entirely sure this would work with foam.