Before making any incisions, we'll lay out the parts on the puppet to get a feel for where things will go. This is a good time to add the USB panel-mount port extender to the micro USB jack on the Feather.
We want to get the speaker up near Lars's inexplicably human-toothed maw, with the Feather board near the center of his back so it is easy to tap it to trigger the sound sample playback.
I decided to place the on/off switch for the enable pin in Lars's right paw-claw-hand thing, and the USB port jack in his left foot.
Use a seam ripper or small scissors to open up the seam on the bottom of Lars's left foot.
To prevent the board from snagging on the doll's batting on the way in, you can wrap the feather in a small bag with a zip tie or rubber band to close off the neck as shown here.
The last thing to push into the plush toy will be the USB panel-mount jack.
Use a medium sized zip tie to secure it to the end of the foot as shown, then trim off the excess zip tie end.
You can now plug a USB cable into Lars's foot for battery charging, swapping out .mp3 files, or even adjusting the CircuitPython code!
Test out your finished puppet now by making sure the Enable switch is clicked on, then tap his back to play!
You may need to wiggle the speaker around to get it to an optimal placement. Also ensure the battery is charged or the USB cable plugged in to get sufficient power.
Note, in the video below I was using a double-tap to trigger.