Much thanks to the posters in this thread for all the good info! Note: Edited to get rid of the Photbucket links.
Have started on my bird…
Skull: Picked up a resin raven skull on ebay that is 3.75" long ($14 shipped). Did a fair amount of work on it: ground off the lower jaw, opened up the nostril hole, filed off the glossy black paint on the beak, then painted it. Here is the skull source:
http://www.ebay.com/itm/262224768223
This pic show the base of the skull and gives hints as to how the spring might be attached:
Bases are 1'" air couplings, also from ebay. Have also ordered a couple 3/4" couplings from the same source to compare the size. Cut off the "feet" and hose clamp tube with a grinder.
http://www.ebay.com/itm/361396993580?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
Springs and nuts
These came from an Ace hardware store. Spring is a bit under 3/4" in diameter and fits the hole in the base nicely. Will need to be shortened a bit. Acorn nuts are M10x8 metric which are just the right size for this skull. 7/16" acorn nuts will probably work as well, but are hard to find.
Windshield wiper arm
Came from a pre '95 Toyota pickup. I drilled out the arm stops and hammered the arm back into the sheet metal piece so the spring mounting hole would be located correctly. This location can be seen in MMFR art book. Then cut off the small small end of the sheet metal piece to match the length of the movie piece. Then bent the arm up and cut it off to match the movie piece.
Left eye
Green cat's eye marbles for the left eye are are coming from ebay.
Zinc/galvanized coating removal
Bases, springs and nuts were soaked in vinegar overnight to remove the zinc plating (and galvanizing in the case of the bases).
Mockup to figure out where to cut the arm.