Tomaselli's work presents compendia of data that surround us, although organised without the hieratic order of any scientific system of reference. The artist amasses thousands of images cut from popular printed sources, accumulating them into subject-related archive sheets before transferring them into his abstract or figurative compositions. Rent from their original scales or contexts, these images are organised into new, larger forms, created through their grouping and doubling. A line of noses, eyes and hands in different gestures, for example, arc from top to bottom of Doppelganger Effect. The picture forms an imperfect Rorschach from left to right that expands out from miniscule, vertical threads of pills, jewel-like paint and flowers in its centre to the very edge of the panel. Like gorgeous torrents of glittering rain, the work constantly shifts in its field of focus, an effect that is furthered by its mirage-like, transparent surface.

Some of Tomaselli's paintings recall stellar constellations, where dark, glossy grounds are punctuated by gleaming spots of colour. Others have more restrained groupings of images, such as Eyes Inverted in Endless Audio, with its seemingly continuous vertical lines of plant leaves, or Colony, with its organic structure of mutating cells. Tomaselli has recently incorporated allegorical figures into his work, such as Adam and Eve in Us and Them, or the Grim Reaper in Field Guides. The figures are described anatomically so that their organs and veins are exposed, in the manner of a scientific drawing, yet these organs are made up of metaphorical matter. In Metal Destroyer, for instance, a work that borrows from Buddhist sculpture, a multi-armed god-like figure has a head composed from thousands of eyes. In this way, detail is often used metonymically, where small eyes or arms are amassed to create a singular eye or arm, or else, as a symbol in a chain of images making the eye rove over all corners of the work. At other times it is metaphoric or literal, joined by delicate, precise painting.

Tomaselli grew up in Santa Monica, California, next door to Disneyland, an experience that has deeply informed his work. For him ‘artificial, immersive, theme park reality’ was a normal part of everyday life. The idea of a ‘contaminated’ image haunts his work, with its post-modern borrowing from high art sources such as Masaccio's Expulsion from the Garden of Eden or Hieronymus Bosch's ghoulish figures combined with a punk, counter-cultural approach. His pictures incorporate multiple reference points and perspectives, effectively condensed into spectacular, dystopian images.