What would be a good example of Kant's "ends only" formulation of the categorical imperative working effectively?

This may be over simplified but “help others before yourself” works effectively. as it meets all three formulations.

It can be applied universally “all able should help others before themselves”.
Your “end” is the assistance of another, the means are your own actions.
You are both legislator and subject in that you have assessed your end as capable of being universally applied while at the same time are subject to it as evidenced by your actions and for that matter the law itself.

Btw, if this is for a class, I want to know what the response is!

This is a simple example, but since ethics is about decision-making, the decision to lie (about anything).

Lying would violate the universal principle because if everyone lied, no one could lie because no one would believe they are telling the truth.

“don’t enslave people”

I think it’s most likely to appear in the negative: you don’t climb on the backs of your co-workers to advance yourself, you don’t profit at another’s expense, you don’t take advantage of reduced-rate services when you can afford the full price, etc.

In practice I think it is virtually impossible to make this principle work because as soon as people cooperate they are all voluntarily working as means for one another.

I’m new to this, so correct me if I’m wrong. The Golden Rule, maybe? Do unto others. . .

@anpy_sueimen, the Categorical Imperative is essentially the same as the Golden Rule in its formulation that says “Act as if you could will your action to be universal law.” But in the formulation that says never to let another be a means, only an end, it says you can’t use people. The question is, what’s a good example where we see this working? I think those are pretty hard to come by.

Thanks for the correction :) I’m trying to think of something positive.
How about giving to charity? Like those trees at christmas with the little cards on them. Where you can buy gifts and return them to the tree for less than fortunate families. It’s not using people as a means, right? Charity is universal, it’s not using anyone. Maybe as an end, though.
I’m so sorry if I’m totally butchering this. I really think it’s a great question.