Just a glimpse of his Manhattan studio makes it clear: The painter Hunt Slonem—the creator of a new line of fabrics, wallpapers, and rugs for Lee Jofa’s Groundworks brand—is a devout maximalist.

Interior designer James Huniford’s first fabric collection for Lee Jofa was conceived for those projects—common in today’s need-it-now world—where waiting weeks for upholstery isn’t an ...