An assembly (10) for crimping a frame (56) of an implant (58) comprises a crimping device (20) with a base (22) and a crimping mechanism (24) that defines a crimping aperture (26). A bath (28) having a floor (30), and one or more side-walls (32) extending upward from the floor to a side-wall height defines a receptacle (18) that is shaped to receive a portion of the crimping device. The apparatus has an assembled state in which the portion of the crimping device has been received by the receptacle, the crimping device is held securely by the bath, and the aperture is below the side-wall height. Other embodiments are also described.