Material nouns

I have read that material nouns are not used in plurals.

Like Copper, Iron, Tin, Wood.

But can we use them with different meanings?

Like

Copper=coin . ( Can I say I have coppers coin?, or I have coppers)
Similarly

Iron=fetters. ( Can I say he was wearing Irons? or irons fetters? )

If no then how can material nouns can be used in plural form?

Thank you

Use can use these:

I have copper coins.
I have coppers.

He was wearing irons.
He was wearing iron fetters.

Thank you.

I have some sentences for correction. How can I correct these sentences?

1-Let the apples lay where they are.
2-I think, I will vote for the President.
3-She is taller than we all.
4-The fruit of his labour is not rewarded.
4-My foot is paining.
He aims to please his customers.

Thank you.

Is this homework, Rida? Have you tried to correct them? What do you think?

I wonder whether I’ve done this properly.

1-Let the apples lay where they are. [color=green]You are correct. ‘Lay’ should be ‘lie’.
2-I think, I will vote for the President. [color=green]The comma should not be used: I think i will vote for the President.
3-She is taller than we all. [color=green]You are correct. You could also say: She is taller than we all are.
4-The fruit of his labour is not rewarded. [color=green]The fruits of his labour are not rewarded.
4-My foot is paining. [color=green]My foot is aching.
5-He aims to please his customers. [color=green]There is nothing wrong with this sentence.

hehehe No, Beeesneees. It is not any sort of homework:)

I like English language and try to learn perfect usage of English grammar. English grammar is my main focus, therefore when I can’t understand anything I prefer to ask someone who knows. Thanks for the help.
Here again I have something to ask that I don’t know.

Is this right to say?

He is addicted to gambling.
He aims at pleasing his customers.
He is afraid of losing his job.

Why “ing” has been used in theses sentences?

Will it be ok if I say?

He is addicted to gamble.
He is afraid to lose his job.
He aims to please his customers.

As you said above that ( he aims to please his customers) is correct, but I have heard people saying “He aims at pleasing his customers”.

Thank you.

He is addicted to gambling. / He likes to gamble.
He is afraid of losing his job. / He is afraid he will lose his job.
He works hard at pleasing his customers. / He aims to please his customers.

‘aims’ does not match with ‘at pleasing’, but as you can see there are other verbs that do!