Solid Hoop pans were developed by Steve Lawrie, Shelly Irvine, and Ron Kerns at Panyard, Inc. in about 2002.
Pans built this way are made on barrels that are constructed from three pieces – a head, a hoop, and a skirt – that are welded together.
This is in contrast to traditional barrels where the barrel is constructed from a head and a skirt that are crimped together, usually with some kind of silicone/rubber seaming compound. The seaming compound often expands and oozes/burns out when the pan is tempered during the construction process, leaving a void between the head and skirt. This void is the source of the buzzing sound found on many pans; and various builders offer solutions such as deforming the pan, dripping vaseline/wax into the join, and so on. The Solid Hoop process was developed specifically and to eliminate this buzz completely from the instrument.
An unexpected side effect of the process is that the pan is significantly more sturdy than one made on a traditional barrel; and as a consequence the instruments are louder and stay in tune longer.
The Solid Hoop process has been copied by a number of builders since it was developed, most notably Alan Coyle.