The flag positions

There are 5 positions for each hand - down, low, out, high and up. Some letters require both arms to be on the same side of the body.
LH = left hand
RH = right hand

(These diagrams are of a person facing you so the left and right sides are swapped.)

A and 1 - LH down RH low

           _ 
          / \
        __\ /__
       /       |
      / /|   | |
  /\ |_/ |   | |
 /  \/   |___|\/
 \  /    | | | |__
  \/     | | | |  |
         |_|_| |__|

B and 2 - LH down RH out
           _
          / \
      ____\ /__
 ____|___      |
|  |     |   | |
|__|     |   | |
         |___|\/
         | | | |__
         | | | |  |
         |_|_| |__|

C and 3 - LH down RH high

  /\
 /  \
 \  /\_
  \/ | \   _
      \ \ / \
       \ \\ /__
        \      |
         |   | |
         |   | |
         |___|\/
         | | | |__
         | | | |  |
         |_|_| |__|

D and 4 - LH down RH up (or LH up RH down)
        __
       |  |
       |__|
       |_
       | | _
       | |/ \
       | |\ /__
       |_      |
         |   | |
         |   | |
         |___|\/
         | | | |__
         | | | |  |
         |_|_| |__|

E and 5 - LH high RH down
                   /\
                  /  \
                _/\  /
           _   / | \/
          / \ / /
        __\ // /
       |      /
       | |   |
       | |   |
       \/|___|
     __| | | |
    |  | | | |
    |__| |_|_|

F and 6 - LH out RH down
           _
          / \
        __\ /____
       |      ___|____
       | |   |     |  |
       | |   |     |__|
       \/|___|
     __| | | |
    |  | | | |
    |__| |_|_|

G and 7 - LH low RH down
           _
          / \
        __\ /__
       |       \
       | |   |\ \
       | |   | \_| /\
       \/|___|   \/  \
      __|| | |    \  /
     |  || | |     \/
     |__||_|_|

H and 8 - LH across low RH out
           _
          / \
      ____\ /_
 ____|___     |
|  |     | / /
|__|     |/ /|
     /\  |_/_|
    /  \/| | |
    \  / | | |
     \/  |_|_|

I and 9 - LH across low RH up
        __
       |  |
       |__|
       |_
       | | _
       | |/ \
       | |\ /_
       |_     |
         | / /
         |/ /|
     /\  |_/_|
    /  \/| | |
    \  / | | |
     \/  |_|_|

J and 'alphabetic' - LH out RH up
        __
       |  |
       |__|
       |_
       | | _
       | |/ \
       | |\ /____
       |_     ___|____ 
         |   |     |  |
         |   |     |__|
         |___|
         | | |
         | | |
         |_|_|

K and 0 - LH up RH low
             __
            |  |
            |__|
              _|
           _ | |
          / \| |
        __\ /| |
       /      _|
      / /|   |
  /\ |_/ |   |
 /  \/   |___|
 \  /    | | |
  \/     | | |
         |_|_|

L - LH high RH low

                   /\
                  /  \
                _/\  /
           _   / | \/
          / \ / /
        __\ // /
       /      /
      / /|   |
  /\ |_/ |   |
 /  \/   |___|
 \  /    | | |
  \/     | | |
         |_|_|

M - LH out RH low
           _
          / \
        __\ /____
       /      ___|____
      / /|   |     |  |
  /\ |_/ |   |     |__|
 /  \/   |___|
 \  /    | | |
  \/     | | |
         |_|_|

N - LH low RH low
           _
          / \
        __\ /__
       /       \
      / /|   |\ \
  /\ |_/ |   | \_| /\
 /  \/   |___|   \/  \
 \  /    | | |    \  /
  \/     | | |     \/
         |_|_|

O - LH across high RH out
       
      /\
     /  \
     \  /\_
      \/ | \
          \ \
      ____\\ \
 ____|___    |
|  |     |   |
|__|     |   |
         |_ _|
         | | |
         | | |
         |_|_|

P - LH up RH out
             __
            |  |
            |__|
              _|
           _ | |
          / \| |
      ____\ /| |
 ____|___     _|
|  |     |   |
|__|     |   |
         |_ _|
         | | |
         | | |
         |_|_|

Q - LH high RH out

                   /\
                  /  \
                _/\  /
           _   / | \/
          / \ / /
      ____\ // /
 ____|___     /
|  |     |   |
|__|     |   |
         |___|
         | | |
         | | |
         |_|_|

R - LH out RH out
           _
          / \
      ____\ /____
 ____|___     ___|____
|  |     |   |     |  |
|__|     |   |     |__|
         |___|
         | | |
         | | |
         |_|_|

S - LH low RH out
           _
          / \
      ____\ /__
 ____|___      \
|  |     |   |\ \
|__|     |   | \_| /\
         |___|   \/  \
         | | |    \  /
         | | |     \/
         |_|_|

T - LH up RH high
             __
  /\        |  |
 /  \       |__|
 \  /\_       _|
  \/ | \   _ | |
      \ \ / \| |
       \ \\ /| |
        \     _|
         |   |
         |   |
         |___|
         | | |
         | | |
         |_|_|

U - LH high RH high

  /\               /\
 /  \             /  \
 \  /\_         _/\  /
  \/ | \   _   / | \/
      \ \ / \ / /
       \ \\ // /
        \     /
         |   |
         |   |
         |___|
         | | |
         | | |
         |_|_|

V - LH low RH up
        __
       |  |
       |__|
       |_
       | | _
       | |/ \
       | |\ /__
       |_      \
         |   |\ \
         |   | \_| /\
         |___|   \/  \
         | | |    \  /
         | | |     \/
         |_|_|

W - LH out RH across high

               /\
              /  \
            _/\  /
           / | \/
          / /
         / //____
         |    ___|____
         |   |     |  |
         |   |     |__|
         |_ _|
         | | |
         | | |
         |_|_|

X - LH low RH across high

               /\
              /  \
            _/\  /
           / | \/
          / /
         / //__
         |     \
         |   |\ \
         |   | \_| /\
         |_ _|   \/  \
         | | |    \  /
         | | |     \/
         |_|_|

Y - LH out RH high

  /\
 /  \
 \  /\_
  \/ | \   _
      \ \ / \
       \ \\ /____
        \     ___|____
         |   |     |  |
         |   |     |__|
         |___|
         | | |
         | | |
         |_|_|

Z - LH out RH across low
           _
          / \
         _\ /____
        |     ___|____
         \ \ |     |  |
         |\ \|     |__|
         |_\_|  /\
         | | |\/  \
         | | | \  /
         |_|_|  \/

Numerical sign - LH high RH up
        __
       |  |        /\
       |__|       /  \
       |_       _/\  /
       | | _   / | \/
       | |/ \ / /
       | |\ // /
       |_     /
         |   |
         |   |
         |___|
         | | |
         | | |
         |_|_|

Annul sign - LH low RH high

  /\
 /  \
 \  /\_
  \/ | \   _
      \ \ / \
       \ \\ /__  
        \      \       
         |   |\ \      
         |   | \_| /\  
         |___|   \/  \
         | | |    \  /
         | | |     \/
         |_|_|

Error - LH and RH raised and lowered together

  /\               /\
 /  \             /  \
 \  /\_         _/\  /
  \/ | \   _   / | \/
 /    \ \ / \ / /   \
|      \ \\ // /     |
|      /       \     | 
 \    / /|   |\ \   /  
  /\ |_/ |   | \_| /\  
 /  \/   |___|   \/  \
 \  /    | | |    \  /
  \/     | | |     \/
         |_|_|