Though the more widely used fasteners are enough for many teams, it is useful to know about the specialized variants.
Spring Pins (or roll pins) are a metal pin that is pressed into a part or parts and are retained due to the very tight fit. They are useful in aligning and holding parts, much like a metal dowel. Spring pins generally have a beveled end that aids with their insertion. There is also a variant (dowel pins) that are solid and do not expand.
Swage nuts are useful to secure a bolt or other threaded fastener to a sheet metal surface, serving a similar purpose as a rivnut. It permanently anchors itself to the sheet metal by permanantly deforming (swaging) the surrounding material. These nuts often require an arbor press for installation, but some variants can also be simply installed via the force of inserting a bolt through it. In industry, this is a somewhat popular method for adding strong, load-bearing threads to a relatively thin piece of soft sheet metal.
Trivia: the swage nut is a relatively modern (patented in 1958) idea, descended from the clinch nut.
Floating Nut Plates
Floating nut plates allow for some small assembly tolerance by allowing the nut some degree of movement. These are particularly helpful when the nut location will not be accessible during assembly. Floating nut plates are usually installed with small counter sunk rivets or bolts.
Sheet Metal Studs
Sheet metal studs lock into the sheet metal once installed and provide a permanent protruding threaded fastener. These are useful when the location can’t be accessed after installation.
Threaded Tube End Inserts
Threaded tube end inserts are an easy way to affix a fastener inside the end of a square or round tube. They are constructed with steel leaves that can be installed (flexed) but not easily removed. Though very uncommon in FRC, these inserts are a viable construction method when working with parts that cannot be secured with gussets.