New projects bring to Fermilab new technological challenges and new solutions. One of those new technologies is the electrostatic septum made with very thin tungsten foils. Electrostatic septa are used in slow beam extraction to separate the circulating and extracted beams. At Fermilab, slow extraction has traditionally taken place as the beam is sent from the Main Injector to the Switchyard. In the standard technology, the septum plane is made as a layer of 100-micrometer tungsten wires. A challenge of the Mu2e project is slow extraction of protons with average beam power of 8 kilowatts. One of the solutions is the new design of the septum. The photo shows a mock-up for studying 25-micrometer tungsten foils under measurement with the laser scanning microscope at the Technical Division.