One of the new realms of practice and exploration offered by these tools is interactivity. We are beginning to shape a new aesthetic language.
~ Simon Penny

The mechanical elements you will bring into your project are often overlooked until the very end, but they should be considered in parallel with the electronic and electromechanical aspects of your creation. At all times, you will need to consider what the environment will be in which your work will exist and what kind of usage it will receive.

Theo Jansen, a physicist turned artist, explores the  kinematics, and mechanics of wind-driven sculptures designed to grab sand from the seaside and continually build up the coast of the Netherlands. They are designed to walk like giant millipedes along the seaside and when one of these sculptures reaches the water collects some sand a wind-activated mechanism switches the direction of the walking and it walks the sand back to the dune and drops it. Then it switches direction again and walks back down to the seaside for another scoop. This is a poetic work of sculpture and the artist has a wish for the machine to mesh with the ecology walking and picking up sand to maintain and manage the Dutch coastline.

In designing these works, Jansen uses artificial life to evolve his walking morphologies. The machines are first visualized using a computer program that tests the kinematics and the relationship of one bendable angle and joint to another. Jansen then translates these designs into sculptures to test his virtual designs in the physical world.

The rhythmic patterns of the walking are visually exciting and Jansen's desire to harness the wind to power these machines makes an important ecological statement. These creatures create a structural coupling between machine, wind, land, and sea. The creatures are like primitive life forms that do not exist without the environment they are designed to inhabit.

The works are constructed with nested electrical conduit, connected with cable ties. The sails, which oscillate and harness the wind, are thin films made of polystyrene. Jansen’s mechanical walking mechanisms, with all the elements moving in sequence, create a visually stunning experience.

One important consideration of design was how they would walk on wet sand near the seaside versus walking on dry sand near the dune. Special pads allow the creatures to walk on the sand. Seawater is salty and corrosive, so the plastic selected to construct the works needed to be salt and water resistant.

Most importantly, Jansen evolved many designs and in the process of testing, he discovered the successful designs. He also has a whole graveyard of designs that are paths on the evolutionary tree that died off, and other evolutionary paths that became the evolved progenitors of his next designs. Engineers and artists can evolve successful designs through trial, error, modification and testing until success if discovered. 

With your work, you must test your works in the environment where they will reside, and if possible the testing should be extensive.

When thinking about the mechanics of your work think about how robust the work needs to be.

• How long would you like your work to function?
• Will there be someone to maintain and oil parts?
• Does it have parts that are subject to wear like pull string mechanics or certain kinds of motors with brushes?
• Will it move intermittently or continually?
• Will it be a warm, hot or very cold environment, or will there be environmental extremes like water or corrosives?
• Will there be dust and dirt in the environment and how might this affect your piece?
• Will there be water or corrosive materials or smoke or have you selected materials that are not complatible such as galvanized screws and aluminum?
• Will children, adults or animals use it? 
• How can you create a work that will last?

Clearly, certain materials are more robust than other materials for making mechanical transmissions. Whenever possible use metal, plastic, and hard woods to create final mechanisms though also consider what will really last given punishing user environments. For mechanical transmissions use bearings and oil impregnated sleeves whenever possible to reduce friction, wear and tear. VBX Inc has a nice variety of bearings.  

Do your initial tests of your mechanism in cardboard and paper to determine physical and simple mechanical relationships as you will be able to solve many mechanical problems before committing to more expensive material. Begin with paper or a cardboard box and exacto knife and cut out circular cams, linkages, rocker arms, levers, etc. to determine the relationships of one mechanism to another and to determine the kinematics. You can often use pushpins and larger cardboard surfaces to see that all the mechanisms do what you expect and move as you desire. You can often use the paper or cardboard as a template when cutting the metal or wood later on.

Cardboard and paper are a great way to create 3D maquettes of the piece or installation you wish to construct. 3D design software, is an excellent method to visualize how a mechanism or installation will mesh with your concept.