Building block fans may want to construct a basic roller coaster out of Legos. There are no Lego brand roller coaster kits on the market as of January 2011, so the construction of one will rely mainly upon your imagination.
Draw a sketch on paper of how the roller coaster will look when done. Figure out how many track pieces will be needed for the size of the roller coaster. The more track, the bigger the roller coaster will be.
Start laying out tracks as you have drawn them. Organise your Lego blocks so that it's easier to try different pieces as you go. Add height or loops to the track to make it interesting.
Try the loops out with a car to see if the height is right. This will also check the curves and loops if you added any . If one car stays on the track, add another car. Keep adding cars until the desired number will stay on the track.
Do not let a child put Lego blocks in his mouth; he could choke on them.