Orlan,
Yes, I got that. And then you will finish with something that looks like a spread of mini cards.
But the original post from BitterBrewer asked for a method where the mini deck could be handled and placed in a mini card box.
With the Lance Burton method (which I suppose use the same principle as Diminishing Returns) you can't do anything but collecting the mini cards an immediately make them big again.

Troels

Ahh, that's because you're missing the switch! That's the reason I linked to the video.
My idea was to do the switch (done before the cards change size - just like in the video), then you spread the deck vertically (apparently a full size deck, everything looks normal), and the deck shrinks as you close the spread and turn it over. You can immediately spread the mini deck. It's a normal mini deck you can use and put in a mini card box.

You only need one full size top cover card (with a little prep work).
Makes sense?

It makes sense to me if you mean you spread the apparently full size deck with the cards turned in the direction of the spread making a narrow spread?
That is possible. Even if it looks a bit strange.

Try with a split deck.

regular deck to two mini decks

Can anyone provide a reference for the fantastic mirror effect above? LOVE IT!

Bob Kings Shrinker from Richards Almanac comes to mind for a shrinking deck effect.

Bob Solari has an effect called "Compressed".

There's a wooden version of a vanishing card box on the big auction now that says you can change a poker size deck to a mini deck...

Julie

I would love to meet the guy who thought up that mirror handling! That is very very clever!

Thanks for sharing, Ryan Lockwood