Defcad, as the firm will be known, has already been dubbed the Pirate Bay of 3D printing.
The site will become a "search engine for 3D printing," according to its founders.
But its flouting of copyright is likely to face legal challenges.
The firm is the brainchild of Cody Wilson, law student and self-styled crypto-anarchist.
Last year he set up Defense Distributed, a project aiming to print gun parts.
The project provoked controversy with 3D printing firm MakerBot pulling gun part blueprints from its website in the wake of the Sandy Hook shootings and 3D printer manufacturer Stratasys refusing permission for its machines to be used by the company.
It is also facing legal challenges to shut the site down.
Despite the set-backs, it released a video this month demonstrating an AR-15 with a 3D printed part firing more than 600 rounds.
Meanwhile its blueprints at non-profit Defcad.org have seen 400,000 downloads since the site was launched, according to founder Cody Wilson.
Announcing the new for-profit Defcad.com at the South by South West conference in Texas, Mr Wilson said it was an obvious next step for the wiki weapon project.
"Help us turn Defcad into the world's first unblockable, open-source search engine for 3D printable parts," says Mr Wilson in the video posted on the website looking for funding.
In the video, Mr Wilson said the revolution which many predict 3D printing will bring about will only happen if it can be freed from corporate ties.
The blueprints available on the site will be for "important stuff", he said. "Not trinkets, not garden gnomes but the things institutions and industries have an interest in keeping from us; access, medical devices, drugs, goods, guns."
"Supplying consumers with blueprints to print products designed by third parties is a business model fraught with risk," said Lorna Caddy of law firm Taylor Wessing.
"Many of those products will be protected by intellectual property rights, such as design law. Owners of those rights could assert them in the courts to prevent their designs being further distributed and to seek financial compensation," she added.

Works by Matisse, Picasso, Gustav Klimt and Ben Nicholson will be offered at auction at Christie's in February, as well as Sting's Steinway piano.
The auction house said the couple had collected the works "with passion and knowledge" over 20 years.
One painting, Nicholson's March 55 (amethyst) could fetch up to £500,000.
The British abstract painter's 1955 work previously hung in the music room at their house in Queen Anne's Gate. It will be auctioned alongside Robert Mapplethorpe photographs, Matisse's Jazz series and Picasso's lithograph Le Corsage a Carreaux.
Prints by Georges Braque and Rene Magritte, as well as well as more contemporary artists such as Carsten Holler, will be auctioned alongside 20th century furniture and lighting by Post-War masters including Yves Klein.
Andy Waters, head of private collection sales for Christie's London said the Queen Anne's Gate home had "effortlessly combined luxury, rarity and colour".
"Each work of art was carefully chosen and the resulting collection is a testament to Sting and Trudie Styler's informed eye for art and design," said Waters.
The couple, whose four children are now grown up, decided to sell the works after buying a new home in London's Battersea power station development. A Christie's spokesperson said they felt it was "time for a change".
More than 200 separate lots are due to be auctioned on 24 February 2016, with estimates ranging from £1,000 to £500,000.
Christie's said the collection also demonstrated the couple's support for young contemporary artists. It includes works by Emily Allchurch and Giles Alexander and a "striking" series of panels by Russian artist Veronica Smirnoff, specially commissioned for the staircase of the house.
The company that developed 3D printed gun parts has announced plans to launch a new firm, dedicated to copyright-free blueprints for a range of 3D printable objects.
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Musician Sting and wife Trudie Styler are selling more than 200 items from their art collection, previously housed in their former family home in London.