I have used this on metal, plastic, metal-to-plastic and it worked very well.  Pay close attention, of course, to an exact 50-50 ratio.  It is a stiff material, compared to the usual epoxies, so a toothpick was handy to mix it completely.  I have used other J-B Weld products and they are all superb.  One advantage of this particular package was its use of two small toothpaste tubes compared to the big hypodermic plunger package, which dispenses the two liquids unevenly and wastes a lot of it.  This sets up quickly but i always let it sit for a day.