A ring which can be fitted with a Sunfilter-Foil (like Baader Sonnenfilter Folie) to use your ETX-105 as a sungazing-telescope.
The foil must be cut in shape (the inner ring can be used as a measurement tool), is then glued onto the inner ring which is then in return glued into the main ring.

I recommend printing the parts using ABS or PETG, as those are more UV resistant than PLA. Also make sure to glue the parts tightly together, test the construction with a strong flashlight BEFORE using it with a telescope for the first time.
To ensure a tight fit, you might have to resize the main ring slightly that it doesn't fall of during use (very dangerous!!!)
The transport protection covers can be held in place by a rubberband, those are essential so the filter foil doesn't get damaged during transport and storing

ATTENTION: Never, absolutely never, use a slightly damaged sunfilter foil on a telescope, this is a great risk to your eyes and can result in a damaged or lost eye. Also, never point the telescope into the sun without a correctly attached filter.