Quote from Kozack2100 >>

Question? 

Do the copper pieces for the eyes count as materials or as a cost. What I am getting at is does the corpse have to keep the copper on its eyes still if the spell was cast via a focus such as a holy symbol. If it's just a material then no but if it's a stated value of a material then you do have to have to coins in addition. This comes into play with transport of the body and did the crew make sure they don't move or does the post death clock resume potentially requiring more powerful spell to bring the character back.

 well I'd assume that copper pieces counts as a cost is indicated for a component, meaning you do need the copper.  It'd be weird to phrase as "two copper pieces each worth 1cp"

So yeah, you need to keep the copper pieces on the targets eyes or gentle repose is canceled, adding interesting flavour to trying to get your fellow to the nearby town. :). passing merchant with dead body floating on a Tenser’s Floating Disk anyone?

Would it extend revivify if its past the 1 minute already?

Yes, it extends the time limit for all raising spells, even revivify.

Scrolls of Gentle Repose can aid a lot when lacking materials for Revivify.

what i wanna know is how well the corpse is preserved? will it just prevent decay or will it also prevent various tiny scavengers that help things decompose? if i cast this on a creature that recently died will the corpse look like it died recently for the duration of the spell? Becuase if so there are a lot of creepy fun stuff an villain could do as a storytelling device

Rangers should have accuses to this spell. It would be a great way to preserve hunted creatures. 

What if you’ve just killed a Lich, find their phylactery, and cast gentle repose on it, can the Lich reform their body?

This is now also a paladin spell, added in Tasha’s Cauldron of Everything.

Quote from Kelain >>

Would it extend revivify if its past the 1 minute already?

 Of course not.  At that point, the corpse has already been dead too long -- the time limit has already passed.  The spell stops time, so to speak; it does not reverse it.

when you are bringing your friend back to town to be revived but you are also 1 cp short of buying a cool item from a traveling merchant

Quote from Kozack2100 >>

Question? 

Do the copper pieces for the eyes count as materials or as a cost. What I am getting at is does the corpse have to keep the copper on its eyes still if the spell was cast via a focus such as a holy symbol. If it's just a material then no but if it's a stated value of a material then you do have to have to coins in addition. This comes into play with transport of the body and did the crew make sure they don't move or does the post death clock resume potentially requiring more powerful spell to bring the character back.

 Up to the DM, but I would run it as if it was a material. 

Quote from jeroen10j >>

You can't cast it on an undead because an undead doesn't count as a corpse. But you could cast it on a undead that you have killed so it can't again be turned into a undead.

 Or other remains seems to imply things other than corpses...

Quote from Pokeedoll >>

If I cast it on an undead do they become just dead?

 No they are just preserved 

Why the copper pieces on the eyes ?

It was a greek tradition in burial so that when you die, you can pay Charon's voyage across the Styx to the hells (where all mortal, good and bad went).

But in D&D Charon is the Yugoloth lord of the merrenoloth, and the Styx goes only around the lower planes. Not good places, not good people.

So you're better staying as a ghost or a soul in the material plane, the Fugue plane (Forgotten Realms), or the shadowfell (Dawn War), than going in the lower planes.

So what are the coins for ? Paying Kelmvor or the Raven Queen ?

There doesn't seem to be a problem RAW.

The coins are for the players to point at and say "I get that reference!" and nothing more.

It's not supposed to relate back to the setting.

Quote from Kozack2100 >>

Question? 

Do the copper pieces for the eyes count as materials or as a cost. What I am getting at is does the corpse have to keep the copper on its eyes still if the spell was cast via a focus such as a holy symbol. If it's just a material then no but if it's a stated value of a material then you do have to have to coins in addition. This comes into play with transport of the body and did the crew make sure they don't move or does the post death clock resume potentially requiring more powerful spell to bring the character back.

 No, if you use a focus to cast the spell, you don't need to have the coins or salt.  Main reason is that this spell can be used on a corpse OR other remains (like a severed hand or a Beholder eye stock).  It states to put the coins on the eyes of the target, but of course no eyes means no coins.  I guess if you or your DM want to keep this requirement during gameplay, the distinction here could be that, if it is a corpse, apply the coins and salt, but if it is a bodily part, just apply the salt.  As for whether the coins are considered consumable material costs, I would say no.  Your not actually spending the material component, since you can simply re-use the coins when the spell ends, and since there are no consumable materials for the spell, you can just substitute the need for it with a focus, as per the core rules.

I wonder if this spell would work to extend the timer for Hand of Ultimate Mercy.

"...But  if a cost is indicated for a component, a character must have that specific component before he or she can cast the spell." [PHB pg 203]

Even though the copper has an implicit gp value it is not explicitly given a gp value. It would be up to your DM whether or not the implied cost of 1/50th of a gp requires that you actually have the two copper pieces but what's difficult about keeping a couple o' coppers in the components pouch, anyway ? 

As for keeping them in place, there is no reason to require that, unless your DM makes life tricksy for you. Afterall, the coppers are not listed as consumed so there is no reason to believe that you would have to keep the coins on the eyes after the casting. Put em back in your pouch and keep things moving, I say.  

Also @ Mr.Shoggs : usually this spell is used within one minute of a character or important NPC's death allowing later use of revivify instead of the expensive and difficult resurrection spell. 

From what I remember about the dustmen, those berks are all for entropy and therefore would probably be philosophically opposed to casting this spell, as it totally spits in the face of entropy.

Now them Harmonioum folks and the sensates most likely wouldn’t be.

Yes the coins must remain in place for the duration of the spell.

Using a spellcasting focus, would negate the need for material components. Would you still need to place the copper pieces for the duration? 

"Casting some spells requires particular objects, specified in parentheses in the component entry. A character can use a component pouch or a spellcasting focus (found in “Equipment”) in place of the components specified for a spell. But if a cost is indicated for a component, a character must have that specific component before he or she can cast the spell."

  - Basic Rules, Chapter 10: Spellcasting - Material