What is the fastest way of doing this kind of feature?
there is a very old feature called Slot
Go to Reuse Library, It's available under 2D Section Library but with different name. You can change the dimensions as you needed.
Regards,Ganesh Kadole#IngenuityIsNX | NX - What's New
you can also create your own reusable object that subtract the slot shape from your model.see in the reuse library the snap example how you can doe that.