A Kentucky jury ordered the manufacturer of a gun kit to pay about $104 million in damages after an 18-year-old who bought the kit through its website used the assembled handgun to take his own life.

The verdict included $4.2 million in compensatory damages and $100 million in punitive damages, according to Dana Mulhauser, a lawyer for the teenager’s family, including his mother, Laura Herp.

The wrongful death lawsuit said that in July 2023, Henry Coby Willis visited the website of Husky Armory, an online seller of pistol-building kits, and purchased a kit to assemble a handgun. The federal authorities later described the seller as operating without a federal firearms license.

According to the lawsuit, the kit arrived at the home Mr. Willis shared with his father. Mr. Willis assembled the handgun in the family’s garage after telling his father he was building a transistor radio. Within six days of receiving the kit, he completed the firearm and used it to take his own life, the lawsuit said.

The suit argued that Husky Armory had sold the kit without verifying Mr. Willis’s age or conducting a background check. According to the family’s lawyers, a federally licensed firearms dealer could not have legally sold him a handgun because of his age and because he would have failed a background check.

The family’s lawyers said the company delivered a firearm kit without a serial number or sales record directly to the teenager. Such firearms are known as ghost guns, as the lack of a serial number makes them untraceable.

The company did not immediately respond to a request for comment. The lawyers and the family said the company, which is based in Omaha, was not present for the trial, according to The Associated Press.

“We’ve made a lot of progress in this country in combating the violence that’s caused by ghost guns, but they are still here, and we do still have to be vigilant in making sure they don’t cause other families, like Henry’s family, to suffer the same damage,” Ms. Mulhauser said in an interview.

Susan C. Beachy and Kirsten Noyes contributed research.