Secondary constraints include structural considerations, as well as the size of the included motor and controller. When two XY cubes are interfaced and aligned, some method of locking them together is desirable. This might be done piezoelectrically, but the baseline design uses four tapered, retractable locking pins extending from one cell to complementary holes in another. There are other mechanical methods of accomplishing the same thing. There is, in addition to the controller, an internal electromechanical interface switch for power and signals.
Energy is delivered to the cell electrically, via roller contacts.
The drive system looked at in some detail is a linear electrostatic motor derivative. The conductor material is unfortunately not specified. Some of the research would, in turn, produce data for better design of the active cell. These features of an XY cube introduce a chirality to the aggregate, and a specific orientation for mutual interfacing. As there are no permitted modes of rotation, this internal orientation is maintained regardless of the configuration of the aggregate.