The steel square is a tool that carpenters use. They use many tools to lay out a "square" or right-angle, many of which are made of steel, but the title steel square refers to a specific long-armed square that has additional uses for measurement, especially of angles, as well as simple right-angles. Today the steel square is more commonly referred to as the framing square. It consists of a long arm and a shorter one, which meet at an angle of 90 degrees (a right angle). It can also be made of metals like aluminum, which is light and resistant to rust.

The wider arm, two inches wide, is called the blade; the narrower arm, one and a half inches wide, the tongue. The square has many uses, including laying out common rafters, hip rafters and stairs. It has a diagonal scale, board foot scale and an octagonal scale. On the newer framing squares there are degree conversions for different pitches and fractional equivalents.

Carpenter's squares are very much like steel squares.

Stairs usually consist of three components. They are the stringer, the tread and the riser. The stringer is the structural member that carries the load of the staircase, the tread is the horizontal part that is stepped on, and the riser board is the vertical part which runs the width of the structure. There are many types of stairs: open, closed, fully housed, winding, and so on, to mention a few of them.

Marc Eckō (born August 29, 1972) is an American fashion designer, entrepreneur, investor, artist, and philanthropist. He is the founder and Chief Creative Officer of Marc Eckō Enterprises, a billion-dollar global fashion and lifestyle company. He is also founder of Artists and Instigators, a venture innovation company, and a partner at SeventySix Capital, an early-stage venture capital fund.

Marc Ecko was born Marc Louis Milecofsky in New Jersey in 1972. He was brought up with his twin Marci and an older sister, Shari, in suburban Lakewood, New Jersey, where his father was a pharmacist and his mother was a real estate broker. The siblings attended local public schools.

In his teenage years, Ecko turned his parents’ garage into a design studio and showroom, creating and marketing t-shirts with his own designs, customizing hip-hop clothing, and airbrushing girls’ fingernails.

Ecko entered Rutgers University’s School of Pharmacy after high school. During his time in college he dabbled in graffiti and became absorbed in drawing, taking “Ecko” for his tag. In his third year, the school’s dean encouraged Ecko to take a year off and pursue his dream. “You don’t want to be 40 with regrets,” the dean said.