Fashion and astronomy lead the way to cost effective tamper protection by Paul Ducklin.
Paul details a very low-tech solution to enable you to detect tampering with your laptop. With the unlikely name “Physically Unclonable Functions (PUFs).”
Saying more would spoil Paul’s surprise. See his post and give it some serious consideration.
You could have explosives, acid protected drives, etc. but sometimes a street light or fence is enough to deter thieves.