Objects of the preposition are always a what?

Dear native speakers. Please, assist me to compose an amount of sentences which describe a definite world. The world looks like this: 1. There is a red hard rough heavy box; 2. There is a green soft smooth light cube; 3. The box is bigger than the cube. Please, use the words from the list: Cube, green, soft, smooth, big, above, close, stand, fast, light, good; Box, red, hard, rough, small, under, far, move, slow, heavy, bad. Sentences can be of any length: from one word to 30 or more. Any suffix, prefix, conjunction, prepositions etc. can be used.

Prepositions are not like other words. The separable prefixes of German seem strange at first. Later they seem like a great idea.

In English there are eight main parts of speech: noun, verb, adjective, adverb, pronoun, preposition, conjunction and finally interjection.

The correct use of prepositions will be the death of me.

After learning a second language, Tom began to second guess prepositions in his own tongue.

In lieu of the preposition "je" one can also use the accusative without a preposition.

Tom was severely beaten by his editor for ending a sentence with a preposition.

All prepositions take the nominative.

He concentrated on his study of prepositions.