This is a big crack that I taped on the outside and did the same process on. The crack is nice and clean so the adhesive worked well enough that I didn't have to put a groove along the outside crack. The plastic did deform a bit though so it isn't exactly perfect but the Thin Ice compound will do the rest.
Here we go tape the outside to make the crack sit flush.
Groove the crack to allow material to fill and make a good plastic weld.
I applied some adhesive, then sprinkled and evened out some powder up and down the crack. Then I put a drop of adhesive every inch along the line of powder. The bond is rock solid.
Since the plastic is deformed a bit from the twisting apart I used some more material to fill and even out the crack on the outside. Once dry I could sand it down a little and then use the Thin Ice compound to make the surface smooth like it should be.
