Unless you're in Califonia or some other foreign country you shouldn't need the 5th. Gun laws are ICC laws and it's perfectly legal for you to manufacture anything you can legally own, for your personal posession (no machine guns, post ban configurations(I think) etc. are allowed. Just what can be currently manufactured by a licensed maker). No paperwork needed, no registration required (as long as you dont want to sell or give it to someone). You can not take them across State lines or transfer them to another person. When you die, they cannot be a part of your estate without BATF licensing and serial numbering. Some State laws may impose restrictions.