Studio series Voyager Class movie Megatron
Plasma canon from Transformers Prime Voyager class Megatron

After repainting the plasma canon, I dremelled a hole in Megatron's arm, then super glued the plasma canon to right arm.

I took another same studio series Megatron and transformed it into vehicle mode and glued the pegs into the slots. Them I took a deluxe Megatron fusion canon, repainted it to mirror the big plasma canon and glued it into the back of the vehicle mode.

In the end, I give you Megatron.