An ink printer cartridge having a press-on lid and the method of make the same is described. An ink reservoir body is having an open-ended cavity and a foam insert is disposed therein. A spacer having a plurality of holes is fixedly attached to the top of the ink reservoir body as by ultrasonic welding. The reservoir is then filled with ink through the plurality of holes in the spacer. A reservoir lid having a plurality of connecting posts is then attached to the spacer by engaging the connecting posts of the lid into the holes of the spacer.