A disposable flow path having a manifold system that provides pressure resistance for the disposable device. The disposable device is comprised of a first rigid plastic sheet and a second rigid plastic sheet. Each sheet has two major surfaces and a thickness between them. At least one sheet surface has flow channels formed in it. The flow channels extend away from a first major surface and beyond the normal plane of a second major surface of the sheet. The sheets are liquid tightly sealed to each other at their adjoining first major surfaces. When each sheet contains a flow channel, the flow channels are aligned and in register with each other. One or more fittings can be secured in the flow channel(s) at an edge of the two liquid tightly sealed sheets. Alternatively, tubing is placed in the channels before the sheets are secured to one another.