The place we visited is Bronzesmith, in Prescott Valley, AZ, a short drive from Sedona. The casting process is a lengthy and labor intensive one. It begins with the artist completing an original sculpture. Greyshoes works in stone.
A rubber mold is made from the original art. A wax positive is made in the rubber mold. That wax positive is dipped in a liquid ceramic silica-sand compound which is cured in a kiln to withstand the heat of the bronze pour. The wax melts during this process hence the "lost wax" name. After the bronze has been poured and cooled, a number of finishing steps occur.
The complete process is here.