just saw this one.....
easiest option is going to be a lockbox for personal effects... If you want to get more complex you could build a steel strapping system.. but thats a little over kill
after that you could set up a easy and cheap mag alarm system, uses a 100db alarm and he'll shite his pants ( like this one
here) you can buy them fairly cheaply and attach them with double sided sticky pad
of if you want to really shock him you could use one of
these.... PM me for more details on how to hook that up....
Cheers
UWSDWF

DISCLAIMER:repeating anything written in the above post may result in dismemberment,arrest,drug and/or alcohol use,scars,injury,death, and midget obsession.