Old chain w/o master link + old tube = seat protector.
Made one for my beater, since it has a Fizik saddle.
Thats the only part worth stealing on the frame.
Since the chain went through the tube, the only way to really take the seat would be to...
1) Loosen the seat post clamp
2) Lower the seat post, to give slack to the chain, to turn it around to expose the chainlinks.
3) Break chain.