Gizmos.DrawCube

Description

Draw a solid box at center with size.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    void OnDrawGizmosSelected()
    {
        // Draw a semitransparent red cube at the transforms position
        Gizmos.color = new Color(1, 0, 0, 0.5f);
        Gizmos.DrawCube(transform.position, new Vector3(1, 1, 1));
    }
}