One trade-off when taking advantage of the high performance of CNC machining processes is that geometric complexity comes at a cost. Simple, chunky parts are the best designs for CNC milling and turning. There will always be some design limitations due to tool access, although the degree of this effect is relative to the number of axes on the machine. In other words, the more axes used, the more complex the features can be achieved.

Another trade-off is that start-up CNC machining costs can be expensive. It is necessary to have a trained professional perform the setup, tool loading, and programming on CNC mills and lathes. Luckily this cost is fixed, so by taking advantage of the same setup for multiple parts, it becomes more economical. Saving money is also achieved by keeping part repositioning to a minimum. Machining at 5-axis and above can sometimes be more economical on multi-faceted geometries because it eliminates the need to manually reposition the part.