Step 1
Cover the underside of the top bunk mattress with a fitted sheet. Then, flip the mattress over and make it as you normally would. The bottom bunk will have a view of a sheet instead of an unsightly mattress bottom. Use colors or images preferred by the bottom bunkmate.
Step 2
Lay panels of fabric, flat sheets or curtains across the top bunk before you put on the mattress. The fabric can dangle over the sides of the lower bunk, creating a canopy. Tie the fabric with simple strips of the same fabric or let the fabric cover the lower bunk for privacy or to create a fort. Dangling fabric may not be suitable for young children.
Step 3
Paint a piece of plywood cut to fit the dimensions of the top bunk. Lay the plywood on the top bunk, then the mattress. The painted plywood could be a solid color or feature, painted designs or stickers such as glow-in-the-dark stars.