[morzh]

Not so good new is, the tool I bought (rivnut) did not work well. Being not a very experienced user of these, I did not realize that M3 nut gripping range is too small, so I used up two rivets only to realize that it snaps under the cap box's hole.

I might throw some good money after bad, I found a kit of coutersunk rivnuts that also has M3 in them. Because the chassis' hole is countersunk, it might help. Well, it is another $17 risk, and I am willing to take it If not, heck, I will use blind rivets. Just have to find some good looking ones.