Finding the point group of Allene molecule

Determination of the point group of allene molecule has been explained in this video with easily understandable diagrams. Without properly scaled models it is difficult to find out the mutually perpendicular 2-fold axes and the dihedral planes of symmetry. But here, by placing the H atoms at alternate corners of a rectangular box and the three C atoms linearly at the centre of the box it has been shown that these symmetry elements can be easily revealed. The point group is found to be D2d.