Daniel Wright, Liam Hall and Stacey Salmon appeared at the Old Bailey on Friday charged with terror offences along with a fourth defendant, Samuel Whibley.
All four were arrested earlier this year at addresses in West Yorkshire, North Wales and Wiltshire.
They appeared in court via video link from prisons in Yorkshire and entered not guilty pleas in relation to 15 terror and firearms charges.
One of the charges – faced by Wright, Hall and Salmon – is the possession of components of a 3D printed firearm for terrorist purposes.
Wright, 29, of Whinfield Avenue, Keighley, West Yorkshire, is charged with offences of disseminating a terrorist publication, possessing articles for terrorist purposes, and the collection of information contrary to section 58 of the Terrorism Act.
He is also accused of possessing and manufacturing a firearm.
Liam Hall, 30, of Hill Top Walk, Keighley, West Yorkshire, is charged with possessing articles for terrorist purposes as well as possessing and manufacturing a firearm.
Stacey Salmon, 28, of Hill Top Walk, Keighley, West Yorkshire, is charged with possessing articles for terrorist purposes and possessing a firearm.
Samuel Whibley, 28, of Derwen Deg, Menai Bridge, Anglesey, is charged with the encouragement of terrorism and disseminating a terrorist publication.
All the offences are alleged to have taken place between January and May this year.
Wright, Hall, Salmon and Whibley denied all the charges.
All four were remanded in custody by the judge, Mr Justice Spencer.
They are due to go on trial on January 11 2022 at Sheffield Crown Court.