These were among the items discovered by police after Lanza, 20, shot dead 20 children and six adults at Sandy Hook Elementary School in Newtown, Connecticut on Dec 14, 2012 after killing his mother, Nancy, 52, at home.
Also found was a holiday card from his mother with a cheque inside for her son to buy another gun, according to five search warrants other matrial made public Thursday.
Lanza went to the elementary school armed with ten 30-round magazines for his semiautomatic Bushmaster .223 calibre model XM15 rifle and bullets for his two handguns and a shotgun, police said.
He shot dead his 26 victims, including the 20 six to seven year old children, in less than five minutes, firing one bullet roughly every two seconds he was at Sandy Hook Elementary School.
Together, the newly released documents help paint a clearer picture of what happened. What they don't explain is why Lanza did it, State's Attorney Stephen J Sedensky III said in a statement Thursday:
"This is an active, ongoing investigation. No conclusions have been reached, and no final determinations have been made," he said.
Meanwhile, recent polling shows public support for gun restrictions has declined since the shooting. Shortly after it, 52 percent of Americans favoured major restrictions on guns, according to a CNN/ORC International poll.
That number has dwindled to 43percent, a version of the same poll conducted between March 15 and 17 found.
Despite a concerted push by President Barack Obama and gun control advocates, no legislation on the matter has passed yet in Washington.
Obama made yet another push Thursday as part of a "national day of action" to galvanize supporters pushing for tougher gun laws.
"This is our best chance in more than a decade to take common sense steps that will save lives," he said at a White House event.
"If there is a step we can take that will save just one child, just one parent, just another town from experiencing the same grief that some of the moms and dads who are here have endured, then we should be doing it. We have an obligation to try."