I had a junker wfc Megatron without a canon, I basically took it apart, panel lined it, painted a few bits black and a few bits red. Then created new canons out of a junker Cybertron Sky Shadow's arms.
The canons come off, Im sure many people here know about the peg that is used to attach the original canon that comes with this figure. I'm using the same peg as the Cybertron sky shadow arm's engines easily slide on to the arms of megatron. for those who wanna try it, you may have to add some extra plastic to get them to stay on solid. So i cut a few parts of plastic from the junker skyshadow and added layers on the inside of the engines so now, they can stay on without being loose, can also take them off.
Not everyone's going to agree with how the gladiator Megatron used to look like, most might say "It's more Megatron still" Then again I don't see many attempts at Megatronus. (I'm not speaking of the Prime)
Comments welcome!
Enjoy!