Here are the parts used (Thanks to Jin Saotome for the idea of using the piece from Robot Replica Megatron):
- Robot Replica Megatron cannon
- Pieces of the Energon weapon from movie scout Air Raid
- "Vengeance" shotgun (from "Ghost Rider" movie figures)
- various cell phone car charger pieces
- rare earth magnets
Movie image:

Finished product (I got the figure elsewhere, I'm not good enough for full figure repaints yet, lol):





Here's a photo of his spear from the movie:

...and my finished product:


I have posted my step-by-steps throughout the process at Tfans and TFW2005, I just wanted to share this with you guys as well.
Thoughts?