Finally, you add in the thumb, just below and to the side of the fingers (the side depending on which hand you are drawing). Description from jamiesale-cartoonist.com. I searched for this on bing.com/images
I love this piece of art as it shows the variation of hands that have been sketched. The effect of this in the format of a sketch book is that you can experiment in lots of different ways on one page to show the reader or the observer how many different techniques have been used to achieve the final piece.
Artist Lui Ferreyra draws colorful portraits of hands and faces, works that use discrete shapes of color as highlights and shadows. These geometric fragments are blended by the viewer's eye rather than the artist's hand, producing color fields that Ferreyra intends to call attention to the connectio