I just bought a Dalvey stainless steel flask on Ebay with integrated collapsible cup.



It's 5 1/4" in diameter and holds 6.5 ounces. They're $108 on the website http://www.dalveydepot.com/dalveyflasks.htm but I paid less than half that on Ebay. It's a little pricey but beautiful and should fit nicely in my TCS Sporran.