Hi Kent,
Again, thank you so much for your feedback and advise. I'm glad to read that you also admire the beauty of the orange tree trick and therefore understand the choice to highlight it into an ace. It is really impressive that you learnt so much about Robert-Houdin and it makes your feedback even more relevant to me. So let me try to continue the discussion for each topic:
Ace of Spades:
It's funny how we came to the same thoughts: I had already attempted to add the magician's hand holding the handkerchief but without finding a satisfying solution to integrate the hand in the spades' shape. Having said that, I gave it another try, while also decreasing the contrast and lowering the brightness of the rabbit to make it merge better with the hat and handkerchief, so that the Spades shape comes better, without the need of adding a background (see my profile picture). I also shifted the rabbit to the left to increase the volume and better follow the shape of the ace. Finally, I added shiny reflections on the hat to make it visually slimmer, and thus more like the Spades base. This was a quick photoshop edit, so it would need more work, but I guess enough to evaluate whether the changes are worth it.
Back of cards:
You're now the second member to mention preferring the black backs. Aside from the aesthetic preference, I reckon that the back of the cards usually match with the back of the tuck box. So following this rule, this is a big argument for black backs. What you noticed on the left and right are actually the legs of the table on which lays the Orange tree. It's rather abstract indeed, but I thought it fit quite well to give structure to the card and introduce the "frame" with the floral flourishes (which also need some work by the way!)
And you mention the using "two or three inter-meshed gears, alluding to both his watchsmith background and mechanical devices." and guess what... that's also what I considered (although only tried it for the front tuck cover background, see next picture). I really like this subtle idea, and I see aesthetic potential to use them as a pattern.
Tuck box:
"As to worrying about black cardboard and yet getting both white and gold foil on the box, you could use white stock, print black on all but the parts in white, and then only add foil. The seal would not
have to be custom-made. But custom stickers shouldn’t be expensive, especially not if sourced through Taiwan."
Yes, I'm also considering doing this, but this leaves white borders of the cardboard, but probably worth indeed. Let's see when I get back to the numbers...
Seal:
This was a draft for the seal... now that I look at it again, it kind of looks like a stamp. What do you think about it? I like the red though, but a gold one could make the link to the gold highlight on the front a bit better, I should try that! And the picture is taken from one of Robert-Houdin's spectacle flyers, but a more abstract picture like you suggested could also work very well.
Ace of diamond:
Yet again a great piece of advice, I could include one of his acts in the center of the curtains. I keep that in mind!
Text below aces:
French it is then
And I tend to think that only the Ace of Clubs should have text on it. It makes this card a bit more special, which justifies more the ace of Club on the tuck box... and I wouldn't know what to write below the other Aces.
Something like this:
"L'oranger merveilleux,
par Jean-Eugène Robert-Houdin"
Jokers
Noted, although considering how much time it took me to draw it, I'm tempted to keep it simple and just mirror it... Ok that's lazy, but this way he lifts the opposite cup. Simple but with at least a small twist"
Remaining ideas for faces:
Thanks, I really like the "elbow joint and/or wrist joint, a pair of engaged gears, and be drawing upon on a pad". Will apply it to one of the queens (Diamond, Heart, or Spades). I also really want to include the coin magic in one of them, but struggle to find how. Any tips?
Ace of Heart:
"One stronger constructive criticism: I don’t think the cards in a circle look enough like a heart for the ace. It's not just the bottom part that isn't clear; the top is also not symmetrical enough and the hand not rounded enough. That could easily be reworked with symmetry, two hands, each fanning a semicircle of cards, for the top of the heart (far clearer), and the cuffs (with tiny heart-shaped cufflinks and the end of an elegant black sleeve). You might be able to work it so that the corners of the cuffs could touch to form the bottom point of the heart; I was going to sketch it for you but am also busy as père Noël"
Hm, noted, but I remember having really struggled already on that one, and although the sketching is still a draft, the shape was really the best I could come up with, without making the hands absolutely unrealistic. So don't rush it, after all, I took 2 years to update this thread, but I'm curious to see your sketch indeed.
Court cards:
"Other than classic style, why have what look like clubs on the crown of the queens and kings of spades and hearts, after all, when that trim could easily be changed to tiny diamonds, clubs, hearts and spades. The classic style would remain, given how subtle the change would be, and yet it would be one more little Easter egg to hide, which could become one of the marvels of this deck –
nearly endless Easter eggs." You summarized very well the intention of that deck haha! Let's add this modification to the list!
Very interesting ideas regarding the Jack as Robert-Houdin's son. I should also spend some time on that.
Added gaffs
"Far too many custom decks don’t have any gaffs added, perhaps just a miserly blank and/or double back. A deck for magicians in particular, as this is the audience this deck will appeal to most, should have a good handful more."
I agree very much. So far indeed only planned to add Robert-Houdin's portrait and quote, but adding a bunch of gaff cards could really fit this deck and I also imagine having it as an option would be the best. Such a great advice, I will also check how it works with the numbers.
You wrote so much that I forgot a few points, but I still have it in mind

Looking forward to update this thread with new development!