A large cube can connect with a smaller if quarter size plates are fitted to one of the larger cubes. The commands to control this complicated robot is still the same as before. They can lift tons - but it depends on the design of the cubes and the size of the cubes chosen. Figures 3 and 4 illustrate a foot sized design that can potentially lift several tons. Figure 3 Figure 4 4.
Strength is dependent on size of cube and design of cube.
Its dependent on what you want to do. If large girders need to be moved, strong cubes are needed - if moving say a laser range finger tool, the laser diode and electronics would only weigh a few ounces and will fit insider a small cube. Several different methods can be used. For magnetic cubes, the units are completely sealed - charge up the batteries and the machines can run around for 10 minutes to several hours depending on how they are used. Animated figure 5 shows magnetic cubes in motion.