This is an empty SR-71 brake chute bay with open doors, as commonly seen after landing. Designed specifically for the Revell kit. The set comes in four 3D printed parts: the main bay, a separate end cap (for easier painting) and separate doors. The door parts have mounting lips and recesses designed in to make the fit as precise as possible. I did successful trials printing the doors as one piece with the container but with the doors separate, it will be much easier to blend the bay with the surrounding plastic.

This set includes a self-adhesive template to precisely mark the position for cutting of the fuselage (you can't simply cut out the scribed doors on the kit, they are completely wrong in size and shape).