Sheet styrene with Unicron joints for articulation.
The head is from a candy pack- heavily modded.

Optimus Prime is 18" tall. He's scratch built with Unicron joints and a modded lollipop holder head. For me this the the perfect scale size for 1:18th he would be about 27' tall. He's very durable and 100% play-ready.
His weapons were scratch made from PVC and plexiglass.
The Truck form is an Ertl truck just repainted with Autobot badges added.

Hasbro makes both Joes and Transformers. Marvel has had crossovers with them, so it was a no-brainer for me to add Transformers to my Joe verse. It could be as simple as members of the Joe team finding the Ark, or as complex as Decepticons hiding out among us. Either way this is like PB and J- the just go so well together. =)