I used transparent PETG for the top sliding cover, and PETG-CF (carbon fiber) for the box itself. I wanted it to be strong. I also added an extra wall and bumped the infill 18%. thew a dime in there for size reference. NOTE! The extra wall makes the sliding action a bit sticky at first, so you might have to slide it back and forth a bit to smooth it out. I wanted it tight for my use. You might consider going with two for an easier slide, but it might not be as secure depending on where you're going to use the box.