This is a protective insert for loaded filters in a matte box.
This print will help protect the filter from any objects that may fall onto the matte box where a piece of tape may not suffice. This also saves on one-time use of camera tape.
As well as protecting the filters in the matte box, it is also a fast and clear way of displaying which camera the matte box belongs to and which backplate it fits onto.
Please see the file names for different sizes available. All the most common size options are listed. The plugs are blank for your own customisation of text or graphics. The plugs are the slightest undersized in order to account for some printer calibrations and tolerances of the back plates.
If you’re UK based camera crew and don’t have a printer please get in touch. Trainees wanting some printed a discount for printing can be arranged.
Link to all the models: https://www.printables.com/model/276857-matte-box-plug