Whew, let's sign out 2016 with a truly tough puzzle! Mr. Chen shows off his tough cluing and unusual long answers. It's also a challenge that the NW and SE corners are nearly completely cut off from the middle diagonal.
1A: Join, as two pieces of metal by application of heat and pressure (SPOTWELD) gets a B- from me. It's an unwieldy clue, with a reasonably good answer. It's certainly not neutral. I like 15A: People on the wrong end of a landslide (ALSORANS) much better. My first confident answer came at 5D: Enamel finish? (WARE).
I love MISCREANT as an answer. 27A: Cosplay and fanfic are parts of it (NERDCULTURE) helped a bit, because I figured out the "nerd" portion early. But even then much of the middle was open, even once I recalled the PERSIANS were on the losing end of the battle of Marathon.
In fact, I filled in the entire SE corner before the middle. I liked this corner the best. 31D: Pistol (GOGETTER) was maybe my favorite of the whole puzzle. It was nice that it crossed HOTRODS.
Meanwhile, I've never heard of UNOBTAINIUM before, but I love it! A substance that is "hypothetical, scientifically impossible, extremely rare, costly, or fictional", according to Wikipedia.
How about 39A: Strips to pieces? (BACONBITS) - hah!
I finished in the NE with ASCIIART. Oof. HARSH!
Anyway, a very good puzzle, which gives me a better feeling than I'd had earlier in this week. Here's looking forward to 2017. Horace will be taking over tomorrow. Which reminds me, Horace, Frances and I are ringing in the New Year in Delmar tonight. Hope everyone has a fun and safe night!