Your pitch could be: "like Regium, except it's not vaporware and actually works."
I mean that company had nothing and they were well on their way to raising 50k, before they were stopped. You have a real product. That $50,000 should've been yours.
https://thehustle.co/03092020-chess-kickstarter-regium/
https://www.reddit.com/r/chess/comments/fcfcpi/the_regium_eb...
https://www.kickstarter.com/projects/soontech/regium-automat...
It's also extremely time-consuming to assemble because of all the wiring required for the magnet sensors, and if you short one of the power connections, there's quite a lot of binary-searching over possible joints before you work out which one needs fixing. I would not like to make another one :).
If you want to buy a commercial one you should check out https://squareoffnow.com/ - it has the advantage that it is actually a product you can buy, but the disadvantages that it has no clock display, no button to confirm your move inputs, doesn't support lichess, and requires use of their smartphone app.
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I bought one Watterott TMC2208 board and found that it was an easy drop-in replacement, compatible with my microstepping configuration, except the motor connectors needed flipping round else they ran backwards (if you're making a drop-in replacement for another product, and you have the option of making the motors move the same way as the other one, or the opposite way, why would you not just make them move the same way? the mind boggles).
Satisfied with this result, I tried to buy another one for the other axis but could not find another Watterott item on eBay, so ended up buying a no-name one, and it looks basically the same except something is weird about the microstepping modes, and I haven't been able to select a microstepping mode that is suitable, so I've given up on that for now. But at least I've got one quiet axis now, and if I come across a Watterott TMC2208 board, I'll know what to do with it :).
I wanted to build one myself, and it was only a complete lack of mechanical know how that stopped me.
I don't fancy bullet chess on it tho...
It's in here, but not for the faint-hearted: https://github.com/jes/autopatzer/blob/master/mojo/lib/Autop...
I did try giving it an accurate model of the acceleration curve of the stepper motors, so that it would do the set of moves that actually took the least time, but that led to strange motions where it would deliberately move pieces too far, and then back again at a diagonal, just to minimise the number of corners it needs to turn, so I instead just made it do a simple shortest-path, because it looks more natural to a human observer.
I.e. instead of going 2 squares right, then 2 squares up, then 1 square diagonal up-left, it would prefer to go 4 squares right, then 3 squares diagonal up-left. It takes less time, but looks stupid.
The problem I faced was that when I had magnets that were strong enough to be reliably grabbed by the electromagnet, they were strong enough to repel each other if they got too close! I went through quite a large selection of different magnet sizes before I settled on the final one (which is 6mm diameter, 6mm tall, neodymium cylinders). They're strong enough to be grabbed by the electromagnet, and weak enough that 2 pieces can be in the centre of a square and a corner of the square without moving apart, but unfortunately still not weak enough that a piece can slide in a straight line past another piece.
When there is a piece in the way, it works out whether it would be shorter to move a piece out of the way, or to route the long way around, and picks whichever is shorter.
If the player you want to spectate will set you up an API key, then yes it can do that.
(Before anybody takes any offence on this, I really hope y'all read Johnny Mnemonic).
Each chess piece has a magnet in the bottom. The board senses your moves by looking at where magnets disappear and appear, and it plays your opponent's moves by dragging them with an electromagnet underneath the board moved by a pair of stepper motors.
https://incoherency.co.uk/blog/stories/autopatzer.html