An apparatus comprises a panel, a cavity extending into the panel, a plurality of overhangs cantilevered from a perimeter of the cavity and catches resiliently projecting from a portion of a floor of the cavity. The overhangs define an insertion opening for a lock. The catches are oriented respect to the insertion opening such that the catches deflect by a first extent when the lock is positioned at a depth within the cavity below the overhangs and such that the catches deflect by a second greater extent during rotation of the lock to beneath the overhangs.