A box shape, four pieces of wood fitted together. Spruce treated 2x4 wood studs, creating a square frame. - Stock Photo - Masterfile - Premium Royalty-Free, Code: 6118-07353285
Amazon.com: Square Box Frame Unfinished Wood Shape Piece Cutout for DIY Craft Projects - 1/4 Inch Thick - 6.25 Inch Size
11" x 11” Dark Oak MDF Wood Shadow Box Frame – FrameWorks
Amazon.com - Shampsen White Shadow Box Frame 8x8 7x7 Square Box Frame with Mat, for 5x5 6x6 Pictures, for Wall and Tabletop Gift for Christmas, New Year, Birthday, Anniversary, Mother's Day, Set