Mornington Peninsula Posse represent... I like cans of cat food hollowed out and stacked. And no, I'm not stupid enough to do it and post it on a forum.
The police have the technology to see through building materials with various scanners. And I would surmise, that it is only a matter of time before the thieves of the world get it also.
Working as a coin dealer in Chicago, we once had a guy come in with a 1,000 oz. bar painted green. He said he had been using it as a doorstop in his home office for years. Another time we had a widow come in with her son. They had many fruit jars full of silver dollars, and one full of $20 gold pieces (over 100). The dear departed husband had buried them all in the back yard a few years, and then been inconsiderate enough to die without leaving a treasure map. The son had had to excavate the entire back yard to a depth of two feet, and they weren't sure if they had found everything. I counted the dollars and there were exactly 2,000 pieces, so I reassured her that hubby had probably just bought two bags of them and split them up.
I use to work with teenage drug and alcohol adicts - I learnt some of the absolute best hiding spots that you never have ever thought of even if you thought about it for a bazzillion years.... Seriously, we were constantly amazed at where they would hide stuff, and how BIG some of the items were, like spray paint cans, bongs... big stuff. I owe my child protection kids a debt of gratitute!
Ill give you one - the hollow of a printer - they put a round spray can in such a way... the printer could still print. I usta hide my 100oz bars that way untill I could get em into the vault.
When I bought my 1st 1400oz, it was split into 2 boxes which I consealed in the roof of my dads house (I don't keep it home anymore FYI ), needless to say, when I went to retrieve it sure enough I lost balance while walking the framework and 700oz slipped my hands and went thru the plaster work and met the floor with absolutely no resistance hahaha