微缩世界数学符号网格

2x2 grid of 4 monumental mathematical symbols built as 3d micro-world reliefs inside circular medallions [Top Left: The Pi (π) as a carved stone relief city inside a metal coin, tiny staircases and colonnades, equations engraved around the rim] [Top Right: The Sigma (Σ) as a mechanical relief with gears and steam vents, patinated bronze, sharp rim lighting] [Bottom Left: The Integral (∫) as a neon rain-soaked micro-alley world inside a steel medallion, reflective puddles, tiny silhouettes] [Bottom Right: The Infinity (∞) as a dust-storm desert relief inside a warm wooden coin, swirling sand texture, miniature rovers] Collector macro product photography, crisp rim highlights, realistic metal/wood grain, shallow DOF, high contrast, swiss 2x2 grid layout.