This is a new silicone Castlemolds mold made by Hirstarts, Mold #282 Cavern Floor Accessories Mold.
An accessory to mold #281. Includes a door, post and arch, rounded ege tiles, a chest and coin pile, 2 wood planks and rectangular stone blocks for short walls.
Mold is approximately 5.5" x4.5", 14cm x 10.5cm.
Mold is designed to work with 25-30mm scaled figures. However, they can work for different scales depending on how you use them. For 16mm figures, use the windows as doorways instead. For larger scales, the blocks could be used as small bricks in a large wall.
You may notice a white residue on the mold, this is corn starch/baby powder. This is to stop the molds sticking to each other.