Method of Tossing Coins for Yin Jing Oracle
The preferred method is to use 50 yarrow sticks.
A shorter method to cast an oracle is the "Coin Method" in which three
old Chinese coins like this one.
The left image is the obv (head) side, and the right image is the rev (tail) side.
The Obv side (H) is "yin" and counts as 2.
The Rev side (T) is "yang" and counts as 3.
This particular coin was from the last years of Qing Dynasty (19081911).
If old Chinese coins are not available, I believe other coins may be used
in their place. However, the method of casting and computation may not
be changed.
The wrong method
Toss one coin to determine one line. Repeat 6 times to obtain a hexagram.
This is not an acceptable method.
Threecoin Method
The accepted method employs three coins. Each toss of 3 coins
determine one line. Repeat 6 times to obtain the hexagram(s) with a
convoluted scheme:
 Toss three coins. There are 8 possible outcomes
 Assign a value of 2 for H and 3 for T and compute a total.
HHH = 2 + 2 + 2 = 6
HHT = 2 + 2 + 3 = 7
HTH = 2 + 3 + 2 = 7
HTT = 2 + 3 + 3 = 8
THH = 3 + 2 + 2 = 7
THT = 3 + 2 + 3 = 8
TTH = 3 + 3 + 2 = 8
TTT = # + 3 + 3 = 9

If the sum is 7, then the line is young Yang.
If the sum is 8, then the line is young Yin.

If the sum is 6, then the line is old Yang.
This is a moving line.
If the sum is 9, then the line is old Yin.
This is a moving line.

The first toss produces the first line, which is placed at the bottom.
The 6th toss produced the 6th line, which is placed at the top.
This is the first hexagram.
 If any of the six lines are moving lines (obtained from 6 or 9),
Then a second hexagram must be constructed as follows:

Each Yin line which is a moving line is changed to a Yang line.
Each Yang line which is a moving line is changed to a Yin line.

Consult the Book of Yi Jing to read the text and commentary corresponding
to the first hexagram.
If there is a second hexagram, consult Yi Jing additionally.