Built of solid 1/2" thick wood this measures 13" high x 7" wide x 6 1/2" deep having two openings 4 1/2" in diameter and a hinged door top and bottom. An inset panel from interior back wall lays forward with free edge resting at the division between the two front openings and due to black interior this is camouflaged.
It is possible the builder started in this position with items hidden behind this open flap. After the items were brought into view this flap will lay down flush into back wall and doors could be opened giving a look through.
Since no instructions were present it is anyone's guess as to actual use. Condition fine.