Recording Sign powered with AA batteries,
using the AA battery holder from Heliox
https://www.thingiverse.com/thing:2339441

Print instructions

Print 100%.
Add a color change after the first layer in the Recording Lettering plate. White first layer, black the rest.
The housing can print with no solid layers, and grid infill 20%
The recording sign plate slides in with a little pressure.
Use a standard hobby horizontal Slide Switch.