Conflict Armament Research says most components such as chemicals and detonators come from companies in Turkey and Iraq, which may not know the parts are being bought by the extremists.
Many components are also used for civilian purposes, such as mining, making them relatively easy to get.
Roadside bombs have long been a weapon of choice among insurgents in the Middle East. IS has made much use of armored vehicles loaded with explosives, which can withstand gunfire in order to reach their targets during battles with conventional military forces.
The most commonly used explosive was made with ammonium nitrate, a common fertilizer. The group's mobile phone of choice, used for remote detonation, is the Nokia 105, the report said.
Most components come from companies in Turkey and Iraq, probably because of their close proximity to the IS group's self-proclaimed caliphate. But the procurement network stretches to 20 countries, with some parts originating as far away as the United States, Brazil, China and Japan.
"They can tap into a lot of commercially available products in the region."
It's unclear whether local distributors, often small companies, knew where their products ended up. The chain of custody is not always documented in full, as some of the producers and distributors did not respond to requests for information, the report said.
The IS group has a considerable amount of military-grade weapons and supplies taken from captured army bases in Syria and Iraq, including machine guns, mortars and U.S.-made armored Humvees. It also likely acquires weapons and ammunition on the black market.
