Optical Drawing Aid

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which is a 21-st century version of a 19-th century Optical Drawing Aid.

The device is a "prism on a stick," a portable lens-like device that is  affixed to a drawing surface, allowing the user to accurately reproduce  an image before them by hand.

The simplicity and brilliance is from the fact that it is a simple prism mounted on an adjustable stand. When an artist looks down through the prism, they see the world in front  of them, plus their hand on the page, combined in perfect  superimposition. In short, a camera lucida allows you to trace what you see.

This image tries to give an idea as to how it works -

source: Lucida Dreams Come True: Kickstart a 21st-Century Version of a 19th-Century Optical Drawing Aid
To know more about it, try this link -> NeoLucida - History

Also, my favourite of some of the cool everyday designs - 

The lid is designed in a way that you can get exactly one Tic Tac in your hand (Something, I recently came to know of)

You could check out 18 Everyday Products You've Been Using Wrong for more of these simple yet useful everyday designs.

Problem: Millions of school children in India do not have desks at school.

Solution / Innovation: A desk & school bag combo made out of cardboard box -- for $0.20 (or Rs. 10) only.

Watch how an NGO made these poor kids in Maharashtra smile: In magical steps a cardboard box folds into a school bag and a desk

Most schools in rural India stand in a dilapidated state. The others that run regularly lack basic requirements like chairs, desks, and proper lighting. Without a desk, these children attend classes sitting on the floor with a hunched back. Poor eyesight, bad posture, and bad handwriting are some of the consequences of not having basic necessities in schools.

An NGO named Aarambh came up with an interesting solution to help school children in rural India. In an extremely effective and economical manner, the NGO collected discarded carton from retailers, corporate houses, and retail outlets. Using a stencil design, the cartons were then folded to form a portable desk known as 'Help Desk', which also doubles up as a school bag.

These bags and desks made of carton were made in less than Rs. 10 and are now being used by these children every day.

"LifeStraw is a water filter designed to be used by one person to filter water so that they may safely drink it. It filters a maximum of 1000 litres of water, enough for one person for one year. It removes almost all of waterborne bacteria and parasites."