rivnuts are great if;
A, they are properly sized
B, they are properly installed in appropriate material
I have this tool that works like a champ, forget that hand lever pull stuff.. the tee handle has a 1/4" drive in the center to attach a ratchet for the larger nuts..
Hand-Driven Tools for Low-Profile Rivet Nuts
and be sure to buy the mandrel set for the thread sizes you're going to use..
when selecting the
nut inserts, pay attention to fastener size, grip length [thickness of material your installing through] and material type..
I've used these for everything from mounting large tool boxes to bed rails to cleats on boat rails.. they work great!
the larger ones like 3/8" steel do take a lot of effort to compress so the right tools make a big difference..
if I can remember, I'll add some pictures from my set in the garage.. I made some examples of a couple of rivnuts in different thicknesses of material to see what a good crush looks like opposed to a bad one..
properly compressed, the nut opening will be centered and very strong, will not spin out when torqued and very easily removed.. they are also less intrusive to a project than adding other members to support or hold something, when the fastener/part is removed, they are very clean looking..
good luck!