Lego bricks can be used to build a perfect symmetrical frame for a quadcopter. Instructables user Weseley used Lego Technic because it has holes in the bricks.
He writes:
“You can mount the motor’s with tie wraps through the holes and it’s an ideal weight reduction. For the motor’s and flight controller I used parts from the famous Hubsan X4.”
Full instructions are available here.
Source: Instructables