Step 1: Legal Stuff
I'm not a affiliate or owner of transformers or Hasbro.(obviously).
I'm not responsible if you destroy your toy or damage yourself.
Step 2: Materials
Transformer toy of your liking or the one in this instructable.
An adhesive (I used epoxy)
A keychain with a screw at the end (check pic)
A drill bit matching the size of the screw end part of the keychain (I used 1/16)
Step 3: Unscrewing
Well its really up to you where you want to put the key chain. But for this instructable, I'm putting it on Bumblebee's left leg.
Locate the screws on the inner left leg and unscrew the two screws there. Don't lose the two screws you will need them later.
Step 4: Drilling
Find the piece that has the wheel connected. The dot is where i plan to drill. Drill a hole throgh the plastic.
Step 5: Adding "Adesive" (Epoxy)
Anyway dip the screw end of your keychain into the "adhesive". Manually screw the screw end into the hole you drilled out earlier. Wait until it dries.