Stackable circuit devices include mechanical and electrical connection elements that are optionally disengageable and disconnectable. The mechanical connection elements comprise pairs of complementary male and female plug-in engagement elements respectively arranged at opposite matching positions on top and bottom faces of each device package. The male and female plug-in engagement elements provide a mutual plug-in engagement. The electrical connection elements comprise a plurality of first and second complementary contact elements respectively arranged in opposite and matching positions on either the top or bottom face of each device package. When the circuit devices are stacked, the first contact elements are respectively configured to provide an electrical connection to a complementary matching second contact element of an adjacently plugged in circuit device. Some of the stackable circuit devices may accommodate an integrated memory die or chip and others of the stackable circuit devices may include line routing and distribution blocks.