Which fastener type is specifically designed to be inserted into a pre-made hole?

A rivet is specifically designed to be inserted into a pre-made hole in the materials being joined. This type of fastener is typically used to bond two or more pieces of material together by being inserted through aligned holes and then deformed, usually by the application of pressure, to create a permanent joint. The design of rivets allows them to grip the materials from both sides of the hole, ensuring a secure fastening.

In contrast, an anchor is used primarily in masonry or concrete applications to secure objects, a cap screw is meant to be torqued with a nut for assembly, and a hex nut is a fastener that complements a bolt or screw and does not function independently to fasten materials together. These options do not have the specific design characteristic of being inserted into a pre-made hole as rivets do.