The pictures show twisted pieces of a metal container, wires, a battery and a small circuit board which exploded close to the finish line at the race.
In another, a piece of charred wire can be seen attached to a small box and a twisted metal lid with bolts.
The FBI said on Tuesday that a pressure cooker may have been used to build the bombs, with nails, ball bearings and other metal packed around the explosive.
The device may also have been hidden inside rucksacks placed on the ground near the finish line.
Special agent Richard DesLauriers said experts would reconstruct the devices at the FBI laboratory in Quantico, Virginia.
Three people were killed and more than 170 others injured after the two explosions around four hours into the famous marathon.
It is not yet known what was used to set off the devices.
Doctors have revealed the extent of the injuries suffered by those caught in the blasts, including details of a nine-year-old girl who lost her leg and a 10-year-old boy who suffered deep shrapnel wounds.
Several people have had to have limbs amputated and others are at risk of losing legs following the blasts. Seventeen remain in a critical condition.
No one has come forward to claim responsibility for the attack and the FBI has yet to find a motive.
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