A method of forming a fluid ejection device includes forming a pair of first glass layers and forming a second glass layer. Each first glass layer includes a first side and a second side with the second side defining a first fluid flow structure. The second glass layer includes a first side and a second side opposite the first side, with each respective first side and second side defining a second fluid flow structure. The second glass layer is bonded in a sandwiched position between the respective first glass layers with each respective second fluid flow structure of the second glass layer in fluid communication with the respective first fluid flow structure of the respective first glass layers to define a fluid flow pathway for ejecting a fluid.