I found this alternative build for the official Lego Bumblebee and Optimus sets on Rebrickable.com, using only the existing pieces of each set!
The designer, Ransom_Fern is an absolute genius. Converting the G1 designs into the Bumblebee movie designs. I highly recommend downloading the instructions. The cost is minimal and incredibly worth it!
https://live.staticflickr.com/65535/...4ecc055711.jpg
