With a font editor you can create a horizontally flipped version of the Percussion font.

Hi Peter, 

thanks for your reply.
After creating a left hand, how can I use it as an expression/articulation?
I have been trying, but without success...
thanks
Andrea

In the example you pictured above, the hand could be either a right or left hand, depending on if you view it from the palm or back of the hand. Are you sure you shouldn't use conventional text such as "Right Hand" or "R.H."? These sissified pictures make a mockery of competent music notation, in my opinion.

Andrea Granitzio,

You wrote:

“… After creating a left hand, how can I use it as an expression/articulation? …”

You create the expression or articulation in the same way as you create any other articulation or expression.

Read in the manual for instructions on creating an articulation or an expression.

NB:

An articulation can be a {font character} articulation.

An articulation can be a {shape} articulation (using a shape created in the Shape Designer).

An expression can be a {text} expression.

An expression can be a {shape} expression (using a shape created in the Shape Designer).

If you decide to create an expression, consider whether it would be convenient to create a new expression category, made especially for this particular expression.