I cracked my Volvo S60 wing mirror off a concrete post the other day, broke the corner into bits and snapped the motor off its mountings. I manged to find most of the bits on the ground but that left about a half inch gap of missing plastic. I was just going to get a second hand one off ebay, but they are about £50, and as the colour coded top cover and glass were in tact I thought I would have a go sticking it back together. I have tried using glue in the past, but its never that successful. So I had a look at DIY plastic wending on YouTube and found this (overly long) video: 25W soldering iron worked a treat. I used other scrap shards of trim (black not grey) from elsewhere to fill in the missing void on the radius. Wasn't expecting it to be so solid afterwards, but its a bit of a winner and very easy to do.