Another option could be stainless sauce cups from a restaurant supply shop. Found 4 oz cups for $1.20 each, they have a slight conical shape and a lip that would make for an easy weld or solder joint. Best I could tell they are 3" dia. & 2" deep. Not as much area as the copper tubes but cheaper & they're one piece.
Michael B.
2010- 6 taps & untold hours boiling over stove, gas grill & open fire. Two gallons bottled & family & friends received early Christmas gifts!
2011- 18 taps & a home built arch (old filing cabinet with steam table pans)
2012- 25+ taps and teaching a Parks & Rec course on Maple Syrup (Yikes!)
Tapping trees here in Bloomington and at a family cabin in Butler County, KY.