You can close the sides for about $32 a rack. I have built 2 racks and closed the sides and back with 1/4 inch birch plywood sheets for $10 each from Lowes. On one I painted them green and on the other black. The nice thing about this design is 4 to maybe 6 screws are needed for each side and can be removed quickly to get more access to the rack, such as moving the temp probe etc.