Some shape features of gears to be manufactured by P/M may be trifling for performances, but important for the stresses level on tools. A FEM study on the effects of design (modulus, teeth number, top fillet ra-dius, relative interference, die height, nuclei material) has been made. The FEM analysis reveals that an in-crease of top fillet radius lessens the Von Mises maximum stresses to levels compatible with nuclei material properties. The application of a DOE approach shows that relative interference may be a critical item, fol-lowed by nucleus material and die height. , No risk of overstressing exists for shrink-fitting rings for ratio between diameters greater than about 4. The results may contribute to improve and optimize the design of spur gears, to be manufactured by PM, without impairing their functional properties and reliability, while re-ducing the risk of tool item failures.