Techniques for bonding structural features together in an enclosure of an electronic device are disclosed. A structural feature may be ultrasonically soldered to the enclosure to provide structural support and form a magnetic circuit within the device. Also, ultrasonic welding can bond various features to an interior region of the enclosure without leaving a mark or trace to an exterior region of the enclosure in a location corresponding to the various features. Further, one or more features can be actuated against the enclosure to bond the one or more features by friction welding. In addition, a rotational friction welding machine can rotate a feature having a relatively small diameter at relatively high speeds against the enclosure to drive the feature into the enclosure and frictionally weld the feature with the enclosure. Also, the friction welding does not leave any an appearance of cosmetic deformation on the exterior region.