Nanocrystalline toroidal cores of the Nanomet alloy are produced by FAST/SPS. Flakes are prepared by milling starting from an amorphous ribbon. An oxidation layer is formed by heat treatment for electrical insulation between the flakes in the compacted toroid. A layer of sol gel is applied to further improve the insulation. The compacted toroidal cores have a density of about 80 %. Low losses of only 50 W/kg at 1 T and 1 kHz can be achieved by using a pressing aid.