Today we will take a look at one such free online tool called IncrediBot (incredibots.com) that allows creation of simple to complex machines once the basics are grasped. The idea behind IncrediBot is to provide basic architectural and mechanical tools in an easy-to-use drag-and-drop browser-based environment which can be used and modified in a number of ways by changing their properties to achieve the desired results. The diversity in options available means the virtually any machine can be built — from a car to a tank, a dumper, a jumper, a crawler, a catapult or even a dancing doll. What's common in all these 'machines' is that they are built using basic shapes connected with each other through joints which can be fixed or rotated, and can also be powered through a motor or piston with their controls associated with the keyboard.

If this all sounds too technical, the guided tutorial is there to help. Start off with the first level — drive a tank. Here, the basic controls of right and left arrow keys to move a pre-built tank combined with up and down keys to move its fork-lifter to pick up debris along the way can be practiced. The second level is shape up, it teaches how to build basic shapes and let them interact over a hill slope under gravity. Simply add a rectangle, a triangle and a circle and let them fall freely. The goal here is to get the circle slide down into a pit on the hill.

The third level actually introduces something mechanical by teaching how to create a basic cart from scratch. Simply add two circles at the ends of a horizontal rectangle and then use 'Rotating Joint' button at the top to add a joint between circles and rectangle — thus making two wheels. These joints appear as small yellow circles, selecting them results in Properties window getting displayed at the left. Check Enable Motor option for the two joints and note that by default, clockwise movement and counter clockwise movement are associated with right and left arrow keys; enabling the motor results in the cart moving right and left when respective arrow keys are used.

The next type of joint is a sliding joint that results in a piston push enabling jump motion, and can be practised in the next tutorial level named Jump Bot.

Then there's a Dump Bot tutorial which guides through the creation of a cart with a dumper arm at the front. You can control it through right and left arrow keys whereas dumper arm is controlled through up and down arrow keys by customising their joint properties. The goal is to lift the objects lying on ground and drop them off the cliff.

The next interesting tutorial is that of a catapult where simply restricting the movement of a stone-throwing arm attached with a base results in a speedy catapult machine sending small green balls far off in the air.

These tutorial levels can be parsed without necessarily completing them. But using them all is a good idea to get a grasp of the basics of IncrediBot tools and their settings. To test robots-making skills, one can take challenges created by other users or create one's own. To make custom machines and robots from a clean slate, the Sandbox Mode button on the main page can be used.

Inside the Sandbox, the play button is used to simulate the robot after which either the pause or the stop simulation buttons can be used to go back to the drawing board. Robots can be saved as well once registration is done, which is instant.

IncrediBot is one truly addictive experience of creating dream machines, solving challenges and sharing games.

Happy engineering!