Things You'll Need
Instructions
Lay a straight ruler against your head to measure the height, depth and width you want your helmet to be. Record the measurements.
Sketch a life-size rectangular sketch of the shape of the bottom of the helmet, based on your measurements, on drawing paper. The result should look like an image of the helmet's imprint on the paper.
Lay thin Legos one round nub wide over the paper outline, covering it, to build the bottom layer of the helmet.
Build up the sides of the helmet with additional layers of thin Legos. Stagger each new layer so that the new bricks bridge across the edges of the bricks on the layer below.
Construct additional layers until three of the sides reach the height measurement you have recorded. Leave the front wall short, about four or five Lego bricks high, to make the ̶0;mouth guard̶1; portion of the helmet.
Bridge the gap over the top of the helmet with thicker Lego bricks two nubs across. Give the top of the helmet a dome shape by building up to the top in a staircase-like manner, peaking at the center, then tapering down to the other side. Create several layers of this arch shape horizontally from the front to the back.
Add an extra layer of Legos over the top of the arches to reinforce them. Stagger the pieces to bridge the gaps between bricks.