The lid is meant to be printed in a translucent and the case in an opaque material. You need to glue them together after inserting the device. It should fit and after gluing it should not move inside anymore. Make sure your printer is calibrated perfect!

You should choose supports for the front and back holes to print clean.

Note: You can partially cover the translucent area to focus the LED. You could even use an opaque material for the lid and drill two holes to see the LEDs below when the case is closed.

This is my very first design and was made with Fusion360. I am sure I did it "wrong". But I was very proud of my first working and useful design :)

The case is also available at GrabCad

The device can be ordered here: Aliexpress or Amazon Germany

You can also get the Model as Fusion 360 File