Far as I can tell, no constitutional right is absolute. Rights to free speech, to vote, have all been subject to limitations and regulations.

I don't see how doing most of the things proposed in this thread would prevent law abiding citizens from buying more firearms. Registering my car, or being required to carry car insurance, or getting a SMOG check every 2 years hasn't stopped me from keeping my car. Likewise, efforts to keep irresponsible people from driving hasn't stopped me from having my driver's license.