I couldn't fin that "trap doors" from cp_well so far, can they be implemented and used as normal (=vertical, resized) doors by adjusting them to a brush?
As far as I'm ware, they're already brushes. If you search "metal" in the texture browser you'll find the texture they use, or use your own, just make two brushes, tie them to a func_door and set their movie directions accordingly.
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