Maybe one of these similar products would be of interest:-
CDHPOWER Gas Frame Tank Cap for Gas Bike Frame/Tank Frame-Gas Motorized Bicycle
CDHPOWER 26 Inch Bicycle Gas Tank Frame - Gas Motorized Bicycle Fuel Tank Frame
CDHPOWER Brushed Alum Gas Frame 2.75L-Gas Tank Built In Frame-Motorized Bicycle
CDHPOWER Gas Frame 3.4L/2.4L/2.75L Gas Tank Built-in Frame-Gas Motorized Bicycle
Brushed Alum 2.75L Bicycle Gas Frame, Gas Tank Built in - Gas Motorized Bicycle