According to court documents, investigators recovered a "fully constructed US Capitol Lego set" from Robert Morss, 27, who is accused of leading other insurrectionists in some of the most violent clashes of the incident.
The Smoking Gun reported that investigators also found a notebook filled with instructions on how to form a militia.
His notebook contained tips and to-do lists that included items like "ambush" and "battle drills”.
On the day of the attack, Mr Morss was wearing tactical gear and a MAGA hat. His goal appeared to be breaching the Capitol's Lower West Terrace, where he and his fellow insurrectionists clashed with Capitol police.
Prosecutors claim Mr Morss "came prepared for violence and then repeatedly led the violent mob attacking."
According to his notebook, Mr Morss planned to bring an assault rifle with four magazines to the Capitol.
Prior to becoming an insurrectionist, Mr Morss was an army ranger and later a substitute teacher.
Though the riot occurred six months ago, investigators are still in the process of rounding up and arresting the participants. Thus far, more than 500 people have been charged in relation to the case.
Prosecutors are currently building conspiracy cases against right-wing extremist gangs that allegedly coordinated attacks on the Capitol. Those groups include the Oath Keepers, the Proud Boys and the Three Percenters. It is unclear if Mr Morss and his group will be subject to conspiracy charges.
Alan Hostetter, another alleged insurrectionist, was also recently indicted and is facing conspiracy charges for running with a militia on the day of the attack.
Mr Hostetter, like Mr Morss, is a US army veteran as well as the former police chief in La Habra, California. He later went on to become a sort of New Age yogi, posting YouTube video instructions for relaxation techniques leading to "peace and tranquility”, according to NPR.
During the height of Covid-19's spread through the US, Mr Hostetter joined along with protesters who opposed lockdowns meant to curb the virus.
Mr Hostetter reportedly grew his movement by blending his New Age beliefs with right-wing extremism and conspiracy theories, including QAnon.
On 6 January, Mr Hostetter allegedly pushed with the other insurrections in an attempt to breach the Capitol. He was arrested last month by the FBI, but has pleaded not guilty to four charges he is facing.
Prosecutors are arguing Mr Hostetter had connections with the Three Percenter militia, which allows them to include him on conspiracy charges the right-wing extremist gang is facing.