Membranes as thin as 500 A were produced from many plastic materials and transferred to frames with dimensions of several centimeters. The self-supporting membranes were obtained using simple-dip-coating techniques. In some cases additional plasma polymerized layers were applied. These membranes can withstand several procedures of photolithography and chemical processing. The mechanical properties of the membranes are similar to that of the bulk material. Some typical applications are described. These applications include the use of the membranes as substrates for thermoelectric detectors and also as beamsplitters and windows for cells employed in CO(2) laser spectroscopy.