This is one part of the roof padding inside the forward section of the lunar module. Six parts like these are necessary to complete the padding. The scale is 1/1, the thickness is 5 mm. For instruction on building the lunar module you can refer to
http://spacemodels.nuxit.net/1-32%20LM/index.htm and
http://spacemodels.nuxit.net/LEM-24/index.htm.
This part is represented in green in the picture above.