Americans will be able to legally publish and download online blueprints for 3-D printed guns at midnight after Donald Trump's administration settled a lawsuit.

US states are set for a legal showdown with the Trump administration in a last-ditch effort to block the public from being able to download the manuals.

Facing mounting pressure, the president says he's "looking into" the issue of the plastic guns being sold to the public because it "doesn't seem to make much sense".

Blueprints for guns including an AR-15-style rifle - a version of the weapon used in a number of mass shootings - are set to go online Wednesday after the government reached a settlement with a company run by a self-declared anarchist.

Cody Wilson holds a 3-D printed handgun called "The Liberator"
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The settlement means Cody Wilson, owner of Texas-based Defense Distributed, will be allowed to legally publish the designs, which would be accessible to people around the world, including the UK.

Earlier this month, he posted a photo online showing a headstone reading "American gun control".

The legal case began after Wilson, 30, posted designs for a 3-D printed handgun called "The Liberator" - made from the same plastic material as Lego bricks - in 2013.

Wilson is fighting 21 states' bid for a temporary restraining order

Trump tweeted on Tuesday: "I am looking into 3-D Plastic Guns being sold to the public. Already spoke to NRA, doesn’t seem to make much sense!"

Twenty-one states have said that

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