How do I secure my Lenovo ThinkPad tablet against thieves when it doesn't have a Kensington lock?
I believe your question is trying to ask 'Are there any laptop security devices out there that do not use a kensington lock slot?' The answer is, Yes.

To see a nice list of various types of locks that are available for notebooks and laptops, please see this website.

I in no way endorse this seller, however they are one of the few sites that seem to have a nice listing of many kensington-alternative locking devices for laptops. I am merely using it for informative purposes.