If you want a belt-and-braces connection between extruded aluminium tubes and the superstructure (beside pop-riveting and gluing them in place, which can be as good as any sword in a stone) you can pass eye-bolts through each insert to create threaded studs like these. You can also pass a pin through the tubing and the eye of the bolt in order to make fasteners that will support bodyweight apiece, should you feel inclined.
I use the method next to fasten the seat plinth to the centre-section of the drone, the studs passing through around a 16" square dimension.
