herflyinghorses & nico6196,
This maybe a better link,
http://www.cbp.gov/linkhandler/cgov/newsroom/publications/trade/iius.ctt/iius.pdf , for sellers outside the USA looking to export to here. It a 211 page OVERVIEW of what must be done by an international seller prior to the item arriving at the US customs clearinghouse, rather than what the stateside customer is responsible for. The are references and sometimes links to more detailed regulations in some sections.
Cut -n- Paste doesn't work on this documtent so here are some pages that have the greatest interest to non-USA based international sellers shipping to the USA on ETSY. But I do suggest that when you have the time to read the full document and any applicable links for your products that it provides.
Page 106 Starts discussing what other US government regulatiory bodies and agencies need done in addition to what the CBP wants before packages are cleared or seized from customs.
Page 115 Specifically discusses that product under the regulatory control of the CPSC can be refused entry for many reasons
Pages 122 to 124 concerns diamonds and precious metals
Pages 125 to 126 concerns the Toxic Control Substance Act, Hazardous Stubstance Act, and Caustic Poison Act
Pages 126 to 128 goes over in general the Textile, Wool, and Fur Act
Pages 132 and 143 discusses what other items that are prohibited from being shipped to the USA without a broker or custom's clearing agent.