the need to avoid feather-edged tooling. Stresses on the edge would cause it to deform under pressing loads and bind against the mating parts of the tooling. (This problem can be overcome by the use of a small flat section.)
• the inability of the powder metallurgy process to introduce re-entrant angle and cross holes. Such features would have to be machined using a post processing step.
• sharp corners should be avoided, being replaced by small radiuses.
• the need to be able to eject the part from the tools after pressing