[baybal2]

Single rotor crafts do not avail for plasticky parts, and require more non-off-the shelf parts in general.

Even very first quads were for example easily makeable with existing toy parts, and plastic.

But with just a bit more efforts, single rotor craft take a lead from quads by a significant margin.

[CamperBob2]

Interesting, thanks. I've never heard this perspective before. So you'd say that anyone building an elaborate homebrew quad -- e.g., the TechIngredients guy at https://www.youtube.com/watch?v=4ZPvZiJLbvI , who generally seems to know what he's doing -- would be better off putting comparable effort (and comparable cash) into a single-rotor aircraft instead?