People who work at a computer all day require the support of an ergonomic chair, but the kind of stool that drafters need looks something like the Ergo Bench by Luis Ferreira.
The main reason why a different sort of seat is best suited for designer is because a lot more range of motion is explored as one makes great pencil strokes and measurements across large plots of paper. A blueprint or a working floor plan may require a closer look, a distanced perspective, and often the draftsman will be getting up and down constantly, bothered by a backrest or chairs' arms.
This particular contraption accounts for the flexibility an artist demands in front of his easel or inclined drafting table. The Ergo Bench can be adjusted in height and angle to offer the perfect perch for the creative genius.