Is there a preposition for "composed of"?

Question

I'm writing a story where there's a federation of minor planets that uses Esperanto as its official language. I'm trying to call them something like "the federation of minor planets", because I'm not creative, and came up with "Federacio de la Planedetoj". However, I'm looking for something that means "composed of", and "de" doesn't seem to mean that. I guess I could make something up about how they specifically chose "de" to emphasize that they're controlled by the minor planets, but I'd still prefer to find a preposition that means the right thing.

TL;DR: What's the word for "composed of"?

Incidentally, if anyone wants to provide a better translation for any other part of the phrase, please do.

Answer 1

As much as English "federation of minor planets" conveys what you intend, also Esperanto "Federacio de (malgrandaj) planedoj" is the adequate expression.

There is no more specific preposition for "composed of". When you speak about something concrete made of certain elements, the preposition el would be the right choice (kuko el faruno, butero kaj ovoj 'a cake made of flour, butter, and eggs'), but it doesn't fit something abstract like a federation.

Answer 2

I imagine, you may like the word Planedetaro as a single word (possibly written with uppercase P to refer to the special federation of small planets). This word does not convey the "federation" meaning, but maybe this is not absolutely necessary.

ar is the suffix to describe a group of similar items, e.g. arbo - tree, arbaro - forest.

Answer 3

The World Organisation of Young Esperantists is called Tutmonda Esperantista Junulara Organizo. In analogy to that you could call it Malgranda Planeda Federacio, or Planedeta Federacio.