Helmet help

[TaterNanners]

Howdy all.  I built this kropserkel helmet some time ago in February, but I never actually finished it.  I assembled it, but then decided I needed to do some more work on it.  Here is the faceplate:

For the snout, I was thinking of painting it and adding a UKswrath microphone greeblie.  My question is: do I need a backplate for the greeblie or no, because the indent is still there?  And if I do, or it is recommended, where could I find some backplates?  I've looked far and wide and I can't find any.

Question 2: here is the back of the helmet assembly.  What can I use to fill in the gaps on the back of the helmet?  I understand that it isn't the best trim job on the back, as this was my first helmet construction ever.

  

[Chopper]

You can actually make a new backing plate out of 2mm ABS. Determine the width dimensions based off of the aerator snout greeb, use a ruler to score and snap the left, right, and bottom edges, then use lexan scissors to cut the top curve. You can use an emory board to file the edges smooth.

The indent can be created using the corner edge of a metal file. Mark the line in pencil, and then pass the file over the line repeatedly until the indent matches.