Hello, thank you for viewing my listing. Since the release of Final Fantasy 7 Remake, I have fallen in love with game, so I decided to start designing some 3D print files to put on display or wear for cosplay.
This is of Tifa's tight wrist cuff, or gauntlet for housing two slots of materia.
Once you have printed this, you could easily modify it to house LED's to make the Materia glow. There are plenty of gems from stores on the internet which would make perfect materia gems.
I have added the files for you to print the Materia, but I'd recommend you either buy some gems, or cast them in resin from some marbles or something. If you would rather print them, then use a resin printer.