Create legislation that requires gun owners to register their gun with the state of their residency every five years.

Every individual who drives a motor vehicle must renew their drivers license and pay a fee. i am proposing that anyone who maintains a weapon register said weapon with their respective state government and pay a fee.
Recent reports state there are 300 million weapons in the US. If the owners of these weapons were required by law to pay a fee ($20.00/weapon x 300M = $6,000,000,000) would be in the coffers of state governments.
If the owners of these weapons were required to take firearm training for each weapon to demonstrate their ability to safely own said weapon there would also be a fee every five years ($10.00/weapon x 300M = $3,000,000,000).
This money would be used to a) identify illegal weapons, b) promote and teach responsible use c) etc.