Here's the basic steps of how to get a BATFE Form 1 which allows you to legally manufacture a suppressor:
Set up a gun trust (copied off internet and went to bank for notary public seal) A gun trust keeps you from having to go to your local Sherrif and get fingerprinted and hopefully get his approval/signature.
Fill out 2 copies of BATFE Form 1 (manufacture a firearm)
Fill out 1 copy of verification of citizenship form
Send 1 copy of gun trust document
Send personal check for $200 payable to "Dept of Justice"
Send everything to address listed on top of Form 1
Wait 4 1/2 months
Forms are available for download from BATFE here:
http://www.atf.gov/forms/download/atf-f-5320-1.pdf
http://www.atf.gov/forms/download/atf-f-5330-20.pdf