Sometimes a design demands a “zero” or very small radius inside corner. This can be completed at minimal cost by designing a “pilot” hole. The rest of the machining can still be completed with large high speed cutting tools.
When designing a part for laser or waterjet cutting minimize “Pierces”. A pierce is where the cutting beam/jet must drill through the material. Each pieces take the same amount of time as cutting a several cm of length. In addition piercing material can damage the surface finish or affect the mechanical properties.