I'm having difficulty picturing the character of Mawhrin-Skel Drone (and Drones in general since they "are floating units of varying size and shape"). I was wondering if there is any artistic representation of him somewhere on the web?
DeviantArt can be a good source for conceptualizations..... I could not find a Mawhrin-Skel but these might help give you a visual:
I haven't found any art that matches what I see when reading the books. Banks almost always describes drones in the same way: metallic oblongs devoid of features or ornamentation. Function over form.
In Excession he describes a drone's "suitcase-sized body." This seems to be the prevailing appearance throughout the series. "People always said drones looked a bit like suitcases but this one reminded Genar-Hofoen of an old-fashioned sledge," he says later in the same book.
In Consider Phlebas: "It was the size and shape of a standard suit backpack."
In Use of Weapons: "The drone was the size - and near enough the shape - of a small suitcase."
In The Hydrogen Sonata: "The drone ... was the size and shape of a large grey suitcase ... rather battered and dusty ... its scraped, slightly dented casing glinted in the sunlight..."
In Surface Detail: "A drone like a small smooth suitcase floated near the woman's shoulder."
In Matter: "The machine looked like a scruffy metal suitcase."
A different design is described in Look to Windward: "The machine was a little less than a metre in height, and half that in width and depth. Its rounded-off rectangular casing was made of delicate pink porcelain held in a lattice of gently glowing blue lumenstone. Beyond the porcelain's translucent surface, the drone's internal components could just be made out; shadows beneath its thin ceramic skin. Its aura field, confined to a small volume directly underneath its flat basse, was a soft blush of magenta..." This appears to be the exception.
Everything I've seen online is perhaps more interesting but not accurate.