I prefer deception over strength sometimes. Embees grandad could have had a false filler neck with a pint of petrol in it. No damage done breaking in and they think they got all there is . Also dummy wallets with useless credit cards and , obsolete foreign banknotes , crap decoy phones and the likes. Lost count of how many old twits I have seen grimly clutching bum bags and handbags that obviously contains all their wealth.
When they could just hand the decoy over to a mugger with a hidden smirk.
Or silly safes that you could open with a tin opener thats say 'here is the good stuff'. unless its actually not.
My brilliant idea for the Jazz was a car cover that disguises it as a builder skip. But I realise it would be filled with rubbish overnight and dent the roof.