A father and son tandem invented a 3-D printing machine to make metal objects. Scott Vader is a mechanical engineer while his son Zack is a mechanical engineering student when they invented the machine.

Existing 3-D printing machines use soft materials for printing. Some people use liquid plastic, food and cells of organisms. To make a 3-dimentional object, there must be a computer design first. The computer instructs the machine to make thin slices of the image to be printed. Then the material to be used is melted. Once the material becomes liquid, the 3-D printing machine drops the melted material. This is done layer after layer until the desired size of the 3-D printed object is achieved, according Science News for Students.

Father and son worked in a basement at their home. They began their project by using aluminum, for material. They chose aluminum because it is soft yet strong. Heat is applied to the object until it melted. A nozzle in the machine squeezed the melted aluminum into the model. It did this until such time that the desired size was achieved.

Some people use metal powders as "ink" for the printing machine. However, this is risky because powdered metal wastes can be harmful to one's health.

Instead of using powdered aluminum, Scott and Zack Vader made use of the magnetic field instead. The aluminum is placed at the tip of the nozzle. Then electricity is run through the metal. The magnet squeezed the metal until it melted and drops passed through the nozzle tip. Layer after layer was added until the three-dimensional object was formed, according to Science-Based Life.

Some critics say that the machine cannot use hard metals because they have high melting points. However, father and son are confident that they can improve and modify their 3-D printing machine so that they can work using other metals such as silver and gold.