Saw these at Potomac and really liked them. No screws, all fit together, easy to clean. Pricey...but I think it's on my list for when my Durawhelp gives out. I really liked it. 4 pieces plus the door and pig rails. Probably still as heavy as a wood box. If I wait for my husband to make mine....I'd be waiting forever. His project list is too long!

http://www.lakesideproducts.com/Whelping-Box-MagnaBox/Whelping-Box-MagnaBox-X-Large-p41.html

Sue Puff