Took an Optimus Prime, and after some effort, decided that since all it does is sit on my shelf, I opted to make him look how I wanted him to look, and forgo his transformation. Cut off all small pegs and such that held him in truck mode. I am particularly pleased that the Beast Hunters Optimus head dremeled down how it did, I feel it truly looks like how he would have if he'd been in TFP. The compartment inside his chest that the Matrix sets in was actually there behind the thick truck windows, and when I removed them to decide how to make his chest, I instantly knew that a Matrix must be included, so I put a (hollowed out) Animated Megs chest on a hinge and BAM! Filled in the lower legs with Gundam pieces.
"Arise, Rodimus Prime!"
Body - Optimus Prime (TFP)
Head - Optimus Prime (TFBH)
Arm cannons - Bumblebee (TFP) / Starscream (TFFoC)
Chest - TFA Megatron
"Wings" - Hot Rod (Classics)
Matrix - Fodder parts
Blaster - Gundam and fodder pieces
Used Gundam fodder parts for body fillers as well.
This is one of my favorite customs to date, so I hope you all like this!