Warden Smith wrote:i think if that was made, i would bump it and then use a plug spinner. still, its a good idea and would mean you would have to carry more kit with you to get into it.
We're talking about a combination dial which needs a key to turn it... like integrating a tubular type lock into the dial, with the shear line where the dial and body seperate, and the spindle running through the center as normal to turn the discs. The dial couldn't turn without the correct key, and if it was picked/bumped it'd only turn a few degrees before resetting.
With that in mind, even if you knew the combo it'd take forever to dial it, and the owner would know it'd been messed with because in all but one configuration the key would no longer work. You'd need to have the key and the combo to open it, or be able to simulate/impression a key to turn the dial freely enough to decode it.

It'd be quite expensive to make because the keys would need to be different for each lock, otherwise someone could just buy one and use their key to free up the dial on others to decode them as normal. If they were able to make something like this and it couldn't be shimmed though, it'd be a hell of a lock.