The design of the aerobots is determined by a number of constraints, among which the weight-to-lift ratio holds the most important place and influences all other characteristics. The lifting force of helium at sea level, at normal conditions of pressure and temperature, is roughly 1000g for 1 cubic meter of helium. For instance, the large non-robotized blimp built in Moncton in 98 (see page "Origins") is a 3,30m-edge structure, which gives about 32 kg of lift ; the total weight of the blimp, made of pink extruded styrofoam, was about 30 kg, so the lifting force is 2kg, which is more than enough to keep it flying.

The size of the first robotized Mascarillon aerobot is 180cm (hence the model name, M180); the lifting force is about 5300g. This may seem a lot ; the M180 is actually quite large, and was designed as a test platorm to allow multiple software and mechatronics tests with minimal concerns about flying abilities. The challenge is actually to built the smallest possible blimp : reducing the edges by a certain factor decreases the lifting power by about the third power of this factor, and the following models, the M170 and the M160, see their lifting power reduced to about 4500g and 3700g respectively. Considering the fact that the load must include the structure (about 1000g), the films (about 1500g), the CPU, the motor controllers, the sensors, the wireless card, the batteries, the motors and the motor ducts, the cameras, the bonding device, and all the wires and cables, it is easy to see that each element must be very carefully chosen in order to maximize its general efficiency.

Apart form theses hydrostatic considerations, many major concerns have to be considered :

1) - The necessity to obtain a perfect cube, with straight edges and flat faces. This is first an art/architecture goal, since it relates to the initial intention of creating perfectly geometrical flying shapes, but it is also induced by the fact that the cubes need to assemble while flying. If the edges are not perfectly straight, or if the faces become convex due to the internal pressure of helium, the cubes will not assemble properly.

2) - The self-assemblage properties. When two cubes connect to each other, they must still be able to use their motors to move in space. The air stream output by the motors of the two cubes must add in order to maintain an adequate thrust. This led to the decision to place the ducted fans at the midpoint of each edge, and to guide the air streams with thin plastic or paper tubes to the corners of the cube.

3) - The axial symmetry of the cubes. The cube is oriented in space : it has a top and a bottom. All equipments is located within the bottom edges and corners, except for the four z-axis ducted fans, which are placed at the middle of the vertical trusses. In order to preserve horizontal stability and to symmetrize the angular momentum of the whole cube, all elements are located within the center section of the trusses and/or at the corners of the cube. Each element must be counterweighted by another element located in the opposite corner or truss center. No helix configuration is allowed : no element can be located off the corners or off the middle section of the trusses, since his would introduce asymmetries in the angular momentum.

4) - The location of the sensors. This is a critical concern. The cube is by no way an optimal shape when it comes to sensory aptitudes, especially with large cubes such as the M180. Obstacle avoidance would ideally require 24 sensors (one for each axis on each edge), which is hard to implement for reasons of cost and energy requirements. The optimal location is still being studied ; three 14-sensors Mascarillons are flying since August 2005.

5) - The need for assembling and disassembling the cubes. Transportation of the cubes is a major concern : these big, hollow shapes would be very costly to move for a demo or an experiment, and since the trusses are also quite fragile, the structure must designed in order to allow the disassembling of the cubes, and their storage in small protecting cases.