An accessory for attachment to a stringed musical instrument that mechanically limits depth of picking action by providing interference to the finger, fingernail, or pick. A plate or “anvil” either flexible or rigid, is adjustably positioned beneath the strings to intercept and arrest a picking element. In a first embodiment, picking depth is roughly controlled my manually forcing the anvil up and down on a flanged support post. In a second embodiment, picking depth may be finely controlled by a knurled thumbwheel or similar mechanism on the anvil support posts. The flexibility of the plate provides a shock absorber, thereby creating a realistic feel to the player. The flexible plate assures both limitation of depth of picking action, and also renders picking action consistent as to depth.