Did these random parts come from a set? Dark grey, dark green, and black turntable Here is a random half made LEGO creation which I bought within a large bag of LEGO. Do you have any ideas what it could be part of?

It is so frustrating trying to identify, but I'm excited at its prospects! If anyone has any tips on how I can figure this out myself that would be appreciated too.
This assembly comes from the Lego Set 76008 Iron Man vs. The Mandarin: Ultimate Showdown.

The assembly can be clearly identified on steps 14, 15 and 16 of the instructions available for example on BrickInstructions.com.

Here is how I proceeded to identify the set:


Spot any less common part (brick type &amp; color), here the Slope 18 2
x 1 x 2/3 with 4 Slots in dark green color. 
Use the BrickLink parts catalogue to look for all sets where that brick is used. Results here.   
For each dark green entry, look at the set inventory and try to spot additional less common parts. In this case, I was trying to find the 4x4 black turntable plate.  
Increase your level of confidence by matching a couple more bricks. The unique 2x4 red brick from the inventory was a good match as well. 
Confirm the identification by finding the assembly by browsing the set 
instructions.