With Democrats declaring that the government is unworkable as long as Republicans control the House and/or the Senate, the president's executive order is the way laws get put into effect these days. Therefore, it shouldn't surprise us to see President Obama's executive order outlawing postings about gunsmithing.
With Hillary Clinton on a glide path to the presidency, we should probably expect her to do much of the same thing regarding gun control, and maybe even attempt gun confiscation. Some gun owners might comply, but many other will try to hold out.
How would the feds make it work without knocking on every door? Well, for starters, she could shift the burden to the states by putting a hold on all federal highway money to a state until the state collected all guns from residents therein.
Licensed firearm dealers would be required to turn over all their buyers' information to the ATF. The federal government would already know who possessed a license to carry. So known gun owners would be told to turn in all guns or face sanctions. Those sanctions would include the inability to register a car, get a license plate, renew a driver's license, obtain or renew any occupation license, or conduct any business with the state.
Pretty soon, fines will pile up on the hold-outs, and they would either face life as a fugitive or turn in the guns. Forget help from the Supreme Court. With a Clinton presidency the court will soon be packed with "living constitution" justices who decide cases not on what the constitution does say as honed by precedent but on what they think the constitution should say.
Meanwhile, for a sample of newly enforced gun control, see Venezuela crushes 2,000 guns in public, plans registry of bullets:
Interior Minister Nestor Reverol said the event marked the renewal of efforts to disarm Venezuelans, through a combination of seizures and a voluntary program to swap guns for electrical goods.
Hmm. One wonders if the reason they don't trade food for guns is there isn't enough food.
Meanwhile, California has found a way to take grandpa's guns away from him. See New Gun Control Idea: Take Guns from Senior Citizens which explains how proponents of California’s Gun Violence Restraining Orders believe "the dangers posed by armed older citizens far outweighs any safety they otherwise gain by owning firearms." Yeah, take away that old man's guns and show him who's in control.