It should be pointed out that smuggling doesn't just involve illegal goods but also includes legal goods that are brought in without following proper procedures such as paying required duties.
https://www.findlaw.com/criminal/criminal-charges/smuggling-and-customs-violations.html
- False Declarations;
- Exporting violations; and
- Importing violations.
False declarations can happen when a person returns to the U.S. or enters for the first time. They must declare the value of any goods they are bringing in from overseas. You can violate the law by misrepresenting the value of the goods, omitting them from the declaration form completely, or making false representations. Also, if you fail to disclose leaving or entering the country with $10,000 worth of currency, you can be criminally charged.
While I am not a lawyer I could see that the authorities might have an issue with someone pulling a stunt like that in order to "test" them. Even if there is no legal issue the person could be put through a lot while they run tests to confirm that nothing illegal is being brought in and there is nothing preventing them from making the process as long and painful as they can.
Something else to consider they also have rules in place for brining other legal objects on board planes if they resemble objects that are not allowed.
https://www.tsa.gov/travel/security-screening/whatcanibring/items/toy-guns-and-weapons
Squirt guns, Nerf guns, toy swords, or other items that resemble realistic firearms or weapons are prohibited. We recommend emptying water guns, which must follow the 3-1-1 Liquids Rule. Replicas of explosives, such as hand grenades, are prohibited in checked and carry-on baggage. TSA officers have the discretion to prohibit any item through the screening checkpoint if they believe it poses a security threat.
It is also possible to be charged with selling fake drugs and the local authorities can bring those charges and it can become their word versus your word about what your intentions are. In this case you might not be intending to sell them but it would be impossible to argue that you are not trying to pass it off as fake drugs.
https://www.criminaldefenselawyer.com/legal-advice/criminal-defense/drug-charges/jail-selling-fake-drugs.htm
Question: I sold a baggie of aspirins that I said was OxyContin to a guy at a concert. After the show, I heard that there were undercover officers in the crowd. Could I be busted for selling fake drugs?
Answer: Yes. States and federal laws make the sale of fake drugs illegal, and you can even be charged with an attempted drug sale under some laws.