Looking for a way to mechanically fasten thin sheet? A new means for doing so has been developed by Penn Engineering (Danboro, PA). It's a self-clinching nut system that can be inserted into a punched or drilled hole, and then squeezed with a proprietary tool or a standard press. That causes a clinching ring on the nut to be embedded in the sheet surface. There is a knurled surface on the nut. (The metal displaced by this embedding step helps hold the fastener in place.) Fasteners can be inserted in sheets as thin as 0.025 in. or 0.64 mm. The load-bearing threads are said to be an alternative to extruded/tapped or stamped threads. (Clearly, it is difficult, at best, to thread such thin sheets.) Nuts are available in steel, stainless and aluminum; thread sizes range from #2-56 to ½-20 and M2 through M10.