Yes to Sellotape! I always Sellotape the cardboard tabs down with one of those tabs of Sellotape so they can be removed to fold it down if you want to keep it for next year. You must Sellotape the cardboard scene underneath otherwise on or about the 20th December it will suddenly fall apart and the tabs will ping out and your their carefully constructed scene will go pinging off all over then place and some vital microscopic part such as the snowmans carrot nose will disappear for ever to much crying and wailing until it is found 3 years later behind the washing machine while moving house, causing you to look like an idiot in front of the removal men when you rush in screaming "I found the snowmans nose!", to a nonchalant "oh, ok, great" from the pre-teen who was so upset 3 years ago