Kensington lock or similar?

Hi everyone,
I'm interested about the rMB but I'm in an office environment where I need to lock the laptop. I currently use the old non-retina macbook pro with kensington port (I've maxed it with 16gb ram and 500gb ssd).
Is there any solution available that is easy and doesn't require to screw a new bottom to the computer? I'm also gonna walk around a lot with it and don't want to be annoyed by extra weight. It doesn't have to be the best safe in the world, just enough to scare away that thief that gets 30sec when no one is in the office.

Thanks