Summary

6 record slots that read records with RFID reader to check if it is the correct record
Songs of correct record play on speaker below each record holder
Hand sensor for someone to place hand on record holder, then song plays

Constraints

1 Raspberry Pi
Limits of I2C
- I2C bus supports up to 128 devices, but limits such as unique addresses, and bus capacitance limit that significantly, especially with longer wire lengths. Something similar to this might have been the issue with the SPI

New RFID readers, flat, I2C, new cable
Speakers
- Already have 3 of 4 ohm 5 W speaker
Speaker Driver
- Complicated, because it is 6 speakers, and different sounds, along with already having I2C used
Hand sensor
- IR distance sensor?
- I2C?
Speaker enclosure

Should the Raspberry Pi control the audio, or should it just send a signal to a separate board to trigger audio playing?
- IE: each speaker has it's own little board with an amplifier and sound file, and plays on command
OR: Should the hand sensor trigger that directly, no need for the Raspberry Pi to control it?
- It could send a signal to the Raspberry Pi so we know what is going on, but this simplifies the code, and I2C issue, and the multiple speaker driver issue.
- Updated Idea: Hand sensor triggers the speaker driver, which has the sound file on it: SpeakerDriver But, the raspberry pi intercepts the signal, to know what is happening, and can turn it off with a mosfet board, or some other way when the correct record in inserted. I think that this keeps it simpler.

IR sensor goes to 555 board, which goes to a transistor. This does this: hand or record placed on the sensor, the sensor goes low, and stays low as long as the object is there. The 555 takes the constant low, and turns it into just a little bump of high. The transistor after the 555 does two things, one: it gets 3.3v from a voltage divider feeding from the 5v powering everything else, and two: it inverts the low-high signal to a always high, triggering low signal (of 3.3v). This will properly (and safely at 3.3v) trigger the board (in dip switch state 010) to play the track, and finish it, but not repeat, as the signal has gone back to normal after it is triggered.
The board will need 5 volts to power the speaker, which we can feed off of for the IR sensor/trigger circuit. Making it all power off of one single 5v rail.
If wanted, we can have the signal voltage also go to a raspberry pi for monitoring, or potentially emergency triggering via a gpio out (manual trigger, not sure how reliable over the distance we would need, the UI would have to swap the gpio to an output, then trigger it, then swap back.) Otherwise, the music player setup is completely self contained.
New RFID boards will go behind the record holders, feeding to the RPI, for solving puzzle. Essentially same as the axe or table puzzle from Odin's Dilemma.