Intonarumori could be regarded as early 20th century, mechanical samplers. Inspired by the non-pitched sounds he heard in his environment in Italy, Russolo categorised them into 6 different families:

1. Rumbles, Thundering, Explosions, Crashes, Splashes, Booms
2. Whistles, Hisses, Snorts
3. Whispers, Murmurs, Mutters, Buzzes, Gurgles, Scuffles, etc.
4. Screeches, Creaking, Rustles, Throbs, Crackles, Scuffles
5. Noises made by percussion on metals, woods, skins, stones, terracotta
6. Voices of animals and people: Shouts, Screams, Groans, Howls, Wails, Laughs, Wheezes, Sobs

The idea was to “capture” or imitate noise sounds with contraptions placed in wooden boxes that could get manipulated with handles and levers to produce a variety of pitches, sonorities and intensities.

For the moment, dear Marinetti, the center of attraction was Russolo with his thirty intonarumori [noise-intoners], Stravinsky wanted to get an exact idea of these bizarre new instruments, and possibly insert two or three of them into the already diabolical scores of his ballets. A crepiatore crackled with a thousand sparks, like a torrent of fire. Stravinsky let out a whistle of insane joy and leapt from the sofa like one of its springs. A fruscatore rustled like silk petticoats in winter, like new leaves in April, like a wind-torn sea in summer. The composer hurled himself in a frenzy at the piano, trying to find that miraculous onomatopoeia, but he tested every semitone with his avid fingers in vain. – Le Serate Futuriste, Cangiullo 

As Russolo’s original instruments have all been destroyed any intonarumorum you will ever see or hear is an interpretation based on literature and descriptions of any of the original ones. Although museums and collectors might rue the fact that the originals have been destroyed, I’m pretty sure that in light of the ideas they expressed themselves the Futurists wouldn’t really have cared as they were very much in favour of renewal and not of holding on to anything from the past. If newer better techniques were available at their time, like tape recorders, samplers or computers, they would certainly employed those.