If you're making a base for your LEGO castle creation, trying to put a nice backdrop behind a train set, or even recreating a scene from Star Wars in LEGO bricks, you may want to put the whole thing on top of a mountain. Mountains are breathtaking landforms that lose little in the translation to tiny plastic bricks—if done well. An impressive mountain range made entirely of LEGO construction toys can be perfect, provided you lay the groundwork correctly.
Plan out the mountain. Measure the model you're working on, if applicable, then determine how tall the mountain needs to be in comparison. Decide on your goal height, then start planning the base. You need a base wide enough to accommodate the mountain growing on top of it.
Separate out a large number of LEGO bricks that are gray, green, black and white from the rest of your collection. Choose mostly gray and white bricks if you want to make a snow-covered mountain. If you can find sloping or angled bricks in those colors, they will also come in handy. Use these bricks to cover the outside of your mountain; build the inner structure out of any color you happen to have left.
Set up the foundation. Build, either on a flat surface or on a collection of LEGO base plates, a wide and flat base for the mountain one-brick thick. Few mountains in the world are perfectly round, so make the mountain base fairly rugged-looking. Offset neighboring bricks by one stud to create curves, and interrupt smooth areas with a sudden jutting brick.
Build another layer of the mountain. Offset this next row by two to five studs, varying to add a level of natural ruggedness to the mountain. Follow the contours of the base layer, but only slightly.
Repeat Step 4 as many times as it takes to reach the summit. From the bird's eye angle, each new layer should look like a line on a topographical map.
Cover the outside of the mountain in the mountain exterior pieces you set aside earlier. Conceal any brightly colored bricks.
Depending on the size of your mountain, you may need hundreds or thousands of bricks. If you will build something on top of the mountain, make sure you have enough bricks left over for the other part of the model. Build in caves or a hinged section of the mountain that you can open to hide a small scene inside.