After selling a bow to a gentleman here that had a new string on it that I did not put silencers on it came to my attention not everyone had figured out how to add silencers yet.  
  So what I do is make mine out of wool yarn.  
Items needed: old plastic hanger, ball of wool yarn, scissors or knife, measuring device.  

First cut your old hanger to look like those in the pic.  Then I tie off the yarn to the underside of the fork.  

After that I wrap the yarn around 10 times.


I then cut off the yarn from the spool and tie a clove hitch around the middle of the yarn.

Next I measure down 10" (pick your own number, sometimes i do 9 or 12)
 

I then split the string by colors at this point.
 

now placed the yarn bundle centered in the split string.
 

now string up your bow, and CAREFULLY cut the loops on the ends of the yarn bundle.
 

Now take the bow and shoot 1-1000 arrows, whatever suits your fancy and the bundles will have puffed up and your bow is now silent and all twang should have been removed.  
 

Yeap thats the way I do it works good except when your wife sees you cutting up close hangers haha  Mike

!!!!!!NOTE!!!!!! remember you do the first part with bow UNSTRUNG. only string up AFTER silencers are in the string.

I like the hanger idea...I've been wrapping the yarn around three fingers for years....good idea

You can also wrap the yarn around a credit card.

Good information there Brian.  I do the same thing but I wrap the wool around a credit card 10 times length wise and stick the credit card between the strands them pull the wool off the credit card.

I never thought about the credit card.d

Same thing here. I use a scrap piece of 2x4 with a couple of paneling nails to run the yarn on.