With the Apple Watch set to ship in aluminum, stainless steel and 18-karat gold, Apple could launch as many as three additional casing materials in time for this fall's holiday shopping season, according to well-connected analyst Ming-Chi Kuo. In a new research note published by KGI Securities on Wednesday, a copy of which was obtained by AppleInsider, Kuo said he expects at least one, but as many as three, new casings to go into production in the fourth quarter of calendar 2015. Those new models, he said, could debut as soon as this fall. The rumor comes on the heels of a separate report which indicated that Apple experimented with platinum casings for the Apple Watch. Platinum watches can often sell for triple the price of gold ones, which would make such a model even more premium than the $10,000-and-up Apple Watch Edition announced this week.