Many of these docs are regularly updated by the FAA so use caution if using these. These are not links to the FAA website. For the most up-to-date copies you should visit the FAA website.
Search for the forms on the FAA website here if you can't find them below
AC20-27F - Certification and Operation of Amateur-Built Aircraft - This AC gives you information and guidance on how to Fabricate and assemble an amateur-built aircraft, register your aircraft, identify and mark your aircraft, get your aircraft inspected and certified, flight test your aircraft, operate your aircraft, receive certification of an amateur-build aircraft purchased outside the U.S. and become a repairman for your amateur-built aircraft.
AC20-139 - Commercial Assistance During Construction of Amateur-Built Aircraft - Explains current FAR and FAA policy for the fabrication and assembly of amateur-built aircraft.
AC39-7C - Airworthiness Directives - This advisory circular (AC) provides guidance and information to owners and operators of aircraft concerning their responsibility for complying with airworthiness directives (AD) and recording AD compliance in appropriate maintenance records.
AC65-23A - Certification of Repairmen (Experimental Aircraft Builders) - This AC provides guidance to builders of Experimental aircraft concerning certification as repairmen.
AC90-89A - Amateur-Built Aircraft and Ultralight Flight Testing Handbook - This AC sets forth suggestions and safety related recommendations to assist amateur and Ultralight builders in developing individualized aircraft flight test plans.
8050-88 - Affidavit of Ownership for Amateur-Built Aircraft - Fill out form.
FAA8130-12 - Eligibility Statement Amateur-Built Aircraft - Fill out form.
FAA8130-6 - Application for U.S. Airworthiness Certificate - Fill out form.
More to come as I get time.