I was asked earlier today what I'd do with a grow/shrink ray. I thought about it a bit, and wanted to share my answer:
First, I'd use a scale to check whether increasing the size of an object increases its mass.
If no, I'd plan to devote the ray's use to the development of otherwise physically difficult or impossible material construction.
If yes, I'd get an object of virtually pure elemental composition, and do some basic tests to attempt to determine whether increasing size proportionally increases the quantity of the same element.
If no, I'd have to do a lot more experimenting to determine the precise nature and utility of whatever new material this device creates.
If es, I'd get a little bit of gold and turn it into tons of gold, which I'd use to bankroll hired security, bodyguards and lawyers. With their help to protect my possession of the device, I'd go to a university with a good lab and get scientists' help doing much more detailed property research about the device's effects.
Next, I'd use it to create vast stores of rare earth metals -- the kind that form much of the environmental costs and material bottlenecks for new technologies. I'd ensure that necessary materials were set aside, earmarked for a 100 percent transition to global noncarbon energy.
After I ensured the massive surplus of rare earth metals, I'd head back to the scientists to attempt to duplicate the device. The reason I delayed this step is because I don't want to risk breaking it before getting the most I can out of it in terms of non-perishible materials.
If it's duplicable the plan is to use it to end food and water scarcity worldwide. I'd start an organization whose priority is to allocate the use of the devices, to end scarcity and prevent hostile uses. (Like using it to turn a non-critical amount of fissionable material to a critical amount.)
If it isn't duplicable, I'd start a similar organization in this case optimizing for the most creative productive uses for diminishing scarcity given the constraints of the single device.
Then I'd retire on the meager revenues of a virtual monopoly on rare earth metals handled with blatantly anticapitalist priorities.