Not a difficult trick to do. Very well explained.
I wish the envelopes were Tyvek. BTW, when I
say "envelopes" I mean you get two different colors - however, you only use one color, your choice.
The spectator makes their choice without the equivoque of "keep that pile; OK, now discard the
one on the left", etc.
There is no deck of cards needed, no shuffling, no Himber wallet. The
card choice is made mentally in a very straightforward manor.