adhesive question

[fluxions.livejournal.com]

So I made these little birds out of shrinky dink plastic:

And now I want to add a pinback to it to make it into a small brooch, but I don't know what kind of glue to use. I tried using Weldbond, which is supposed to glue all sorts of things lincluding glass and plastic and tiles. It worked at first, but if you mess around with the pin too much (like push it to one side), the pinback pops off easily.

I went to thistothat.com to see what they recommend, but for metal to plastic they were recommending all these metal epoxies. I don't think I really need something like for a tiny project like this. I need some industrial strength adhesive to make it really stick. Any advice?