I have an idea for an effect which would require secretly exchanging one small packet (5 to 6 cards) for another such packet. I’m not much of a sleight-of-hard card magi, so I’m hoping to find some sort of prop or gadget that can do the job cleanly, automatically and undetectably.

One of those standard hinged card boxes (with the inner flap/false bottom) might almost do, but so far as I know they’re all designed and intended to just work with the thickness of only one single card, rather than a packet of 5 or 6 cards. Is there a “deeper” version of such a device available?

Basically, what I’m looking for is the card equivalent of a Quiver purse — one that secretly swaps a few cards, instead of a few coins.

Himber wallet? Z-fold wallet?

You know, in all my years I’ve actually never owned, handled, or even seen (in person) a Himber wallet.

Can they handle exchanging not just a single card, but a packet of up to six cards?

Yes, a good one can. There are many different good ones out there.

A Shogun Wallet would do the trick, I think. Switching is what it is built for. There's also Mark Mason's "Switcheroo" and the update, "Switch a Two" (not sure if I spelled the second one right), which do the work automatically in your breast pocket. You'll need to check if Mason's gimmick will work with that many cards, but I've tried it (the first one) and it works great.

I agree with Chessman with those options also. In the long run though, it boils down to the routine.
Will it be odd to be using a wallet? Is the packet of cards taken from a full deck to begin with? I have used a Budda Money Paper trick to carry some cards which allowed for a switch. are you wanting to use the card box as the switch device? Though it is sold out at the moment, Ellusionist has Parson Switch Box, Penguin Boom Box by Andrew Neiner; both tools are a card box.
You mentioned something about a Quiver, Quiver does have a Quiver Himber Wallet also (though it too is sold out) for a decent price. Feel free to pm, I would be happy to bounce ideas back and forth instead of here in the open forum.

Context is key, yes.

My idea is to do a Princess Card Trick by switching out the whole packet (minus one, of course), rather than using double-ender cards. With no gaffs in play, the cards can be fully spread (not merely fanned) both before and after, and are always fully examinable.

So I just need a good way of secretly swapping one small packet for another small packet.

My thought was: put the packet in a wallet (or envelope, or whatever), then “pull the trigger” (i.e., “shoot” one of the cards), then take them out to find the mentally chosen card missing.

For convenience and ease, look into switching envelopes.

Https://www.youtube.com/watch?v=XB_x0G3ZHDg

The Princess Trick is so simple and direct, I don't see how you could get away with a switch. If you put the packet in an envelope etc. and theirs disappears, surely the method would be obvious?

There are versions of Thought Of Card(s) Across that work in the way you want; but they are less direct than the Princess Trick. The procedure is more complicated, which creates the opportunity for the method.
EG Michael Ammar -
https://www.youtube.com/watch?v=gf-Hx2Tp7ME
David Garrard -
https://www.youtube.com/watch?v=vyosnr1Azhk


CROSSED THOUGHT is very direct, like the Princess Trick.
https://www.youtube.com/watch?v=_Jt_iLoElTs

In the Princess Trick, the magician openly removes a card and puts it in his pocket. Whereas in Crossed Thought one of the cards disappears by magic. Then it is revealed to be in another packet held by a spectator. This would give you the misdirection needed to end clean with a simple switch. The crucial point is that you would be doing this after the magic has already happened from the spectators' point of view.

Nikodemus has some valid points with using the Cards Across plot, yet the thought of card reappears. It is my interpretation of the OP's desire to have their thought of card just be gone, poof, vanished; instead of reproducing it from a pocket or its' reappearance elsewhere.
I don't know the routine karnak has in mind, yet I envision something along the lines of demonstrating it, as does Bill Wisch in this video


Now, imagine if you will, the last person is asked to think of one of the cards and instead of removing one card, the packet of cards are placed into an envelope and handed to the participant. A souvenir, perhaps write the name of the card you thought of onto the envelope? When they open the envelope later (if they want to), there are only 4 cards and their card is gone.
Is the payoff worthwhile? Instead of Schrodinger's Cat, it would be Schrodinger's Card... their card is and isn't there until the envelope is opened, and then, once it is opened...

Several options have been put on the market, from double ended card cases to classy looking mirror glasses for parlor/formal shows… there’s also a nifty jacket or shirt pocket switch device.

The idea of doing the prince’s card trick with a repeat using a packet switch is sound.
Geoff Latta mentioned one where you have to pull out the correct card at the end because… well it was a long time ago.

I know this method is not always applicable, but I am enamored with the "both hands go into jacket pockets to look for the case" switch. Harder to do with a packet of loose cards vs. a single card or rubber-banded packets, but not impossible.

The problem with all the methods mentioned above (wallets, envelopes, pockets, glasses etc.) is you would be doing the switch when all the heat is on the cards.
The reason the card just disappears each time in the Bill Wisch video above is because (I presume) he is using gaffed cards, and not doing a switch. The gaffed cards are what make it so clean.
Doing a switch afterwards to clean up seems like a viable option. But I can't see how a switch could be used instead of the gaffs.

It would work for Cards Across because there are TWO packets to be counted - so there is natural misdirection.

Nikodemus, if the cards are taken out of an envelope to begin with and after doing a multiple demonstration, to replace the cards back into the envelope, handing it to the last person as a give away?

The swapping of two subtly different packets is intended to enable a fairer display of all the cards — not just in a fan, but with the cards separately dealt in a non-overlapping row. That, to me, seems an improvement over the original, in which the cards cannot be freely separated (much less handled and examined by the spectator — which to me also seems to be yet another advantage over the original, non-packet-switching approach).

But to me, perhaps the biggest weakness of the original Princess effect is its whole business of first pocketing a card, and only then showing that the mentally selected card is now missing from among the remaining cards.

Maybe it’s just me, but once the initial shock wears off, if I was the spectator then I’d immediately be saying, “Well, that’s an oddly roundabout way of indicating that you found my mentally selected card. Why not just name it outright — or pull it out of the fan and show me its face? Why coyly go to your pocket with it? And anyway, now that the magic is over, why can’t you just go ahead and take my chosen card back out of your pocket right now, and show me its face — for final and total confirmation? Hmmmmm?”

On the other hand, if their chosen card instead simply and completely vanishes altogether (thereby leaving one less card in the fan than it started out with), then it’s no issue. There’s no pocketed card for a spectator to get suspicious about, when you refuse to simply bring it back out and show it to them.

Does no one ever encounter the “Let’s see that card that you put in your pocket” deal-breaker?

An interesting Princess Card Trick reference is titled The Impostress Princess, self-published by Chicago area magician Peter W.Tappan, copyright 1986. This little book (114 pages) was recommended as "One of the best books on magic I have ever read" by Charles Reynolds.

Tappan offers several variations on the theme and various methods of achieving the desired effect.

Though The Impostress Princess is a good book, it is not for the packet Princess Card Trick using 5 cards.

The book referenced is using a whole deck of cards and discerning thought of cards by different persons.

If by chance one is interested in such, there was an expanded version published in 2011 also.

I've forgotten details, but there was another book from this approximate time frame that followed more closely the standard Pricess Card Trick premise.

Does anyone remember the author etc. of this second book?