Place four 12-inch sections with 4-inch diameters on their circular surfaces. Consider them the posts of the bed. Arrange and space them so they form a rectangle that measures 37 by 80 inches. Place an 80-inch log section with a 3-inch diameter across two of the posts, to serve as the long support boards for the bed.
Drill two holes through the top of the long support boards and into each of the four posts. Position 5-inch wood screws with a washer in the holes, and screw the screws through the long support boards and into the post.
Set eight 37-inch log sections with 1-inch diameters on top of the long support boards. Space these log sections, which are the mattress support boards, evenly across the long support boards. Drill a hole through each of the mattress support boards and into each of the long support boards. Set a 3-inch wood screw with a washer in each hole and tighten those screws completely to secure the mattress supports to the long support boards.
Apply a thin coat of sealant to the bed logs using smooth, even strokes. Work the sealant into each of the spaces between the logs, covering as much of the surface as possible to help preserve the bark. Let the sealant dry for two hours and apply another coat of sealant.