Do you have a lot of half-made Lego sets and stray Lego bricks lying at the bottom of your toy bin? Many kids don't know what to do with all their old Lego pieces, and some kids have a lot of them. But a new book can help you give your old bricks a new life.

"The Lego Ideas Book" is full of cool creations, from monsters and spaceships to castles and cars -- all made from random Lego pieces, not from specific sets. Some of the featured builders are experts who work for Lego, but others just build Legos as a hobby. With a little imagination, you can start building this way, too.

"We like to think that pretty much any set that you have, you can take apart and make something totally different from that original set," said Daniel Lipkowitz, the book's author.

Here are some tips to help get you going. But first you've got to fish all those pieces out of the toy bin!

>Start by sorting

It really helps to sort your collection into different types of pieces, such as regular bricks (the square and rectangular pieces), interesting shapes and connectors, and then unique items (such as wheels, windows and plants). You can also sort your bricks by color. But it takes a lot of small containers to keep your collection organized that way!

>What to build

Take your cue from your collection. If you have a lot of little wheels, for example, "that could work for a space vehicle of some kind, like a moon rover," Lipkowitz said.

If you have a lot of windows from a Lego City set, you might try to start with a cool building. If you have some Lego plants and bushes, perhaps you could add an environmentally friendly "green" roof, covered with plants.

But sometimes it's best to just grab a handful of bricks from your pile and start putting them together to see what you come up with.

>Learn how pieces work

The basic brick, no matter which size, will form the core of your structure. But look for some of these bricks that can help create great models:

Bricks with side studs: These are just like basic bricks, but they have extra studs on the side, which allows you to attach bricks in two directions. It's great for adding elements to the outside of your structure, such as a wing or the side of a wagon.

*Plates with bars: This simple piece can do so many things. Lock it with a clip plate (like the Lego hand piece) to make a hinge for a door or a knee joint. Or it can be a handle, a railing or toes on a robot!

*Tiny detail pieces: Your creation doesn't have to be big. The book has many examples of building in "microscale." With this technique, a single angled brick can form the nose of a tiny spaceship -- or the tail of a duck.

>Fire up your imagination

The key to this kind of free building is not to worry that you might be doing it wrong. You'll learn what works the more you try it, and soon you'll figure out ways to use pieces in really creative ways. And that's the goal, Lipkowitz said. "The book is all about inspiration and thinking of new ways to use the pieces you have."