The author was listed as C J Awelow, a name without much of an online footprint.

The book was available until last week, when Amazon removed the listing, saying that it violated the company’s content guidelines, without specifying which ones.



The courts might be unable to stem the spread of the existing blueprints, but they may help contain its evolution, said Philip J. Cook, a public policy professor at Duke University.

“A lot of the concern has been that the technology is going to evolve if there’s a free exchange of ideas,” he said. “And that’s something that could at least be slowed down through a ban on the distribution of this kind of information.”

Mr. Wilson is seeking $400,000 in donations to defray his legal costs.

His legal problems started after he successfully test-fired his plastic gun, called the Liberator, in 2013 and posted blueprints for making the gun with a 3-D printer. The plans were downloaded some 100,000 times before the State Department stepped in, telling Mr. Wilson that he was violating export rules governing sensitive military technology.

Later, he joined with a gun rights group, the Second Amendment Foundation, to sue the government for violating his free speech rights. In June, after Mr. Wilson suffered a series of legal setbacks in the case, the State Department settled the lawsuit and gave him the go-ahead to post the blueprints and offered to pay nearly $40,000 of his legal expenses. The reason for the settlement, the government said, were changes in how the State Department regulates weapons exports.

Gun safety activists quickly raised an alarm, contending that the reversal was a sign of the administration’s favoritism for gun interests. They filed public information requests for details of how the State Department decided to settle but have yet to hear back, they said.

On Capitol Hill, bills to block downloadable firearms have been introduced in both houses.

The state attorneys general who filed suit in Washington State said that online gun blueprints would complicate enforcement of firearms regulations, which vary from state to state.