This is a whelping box I built for a buddy. It’s made out a air handler box, so it’s metal and insulated. There’s the door for the gyp to go in and out and to the left of that there is another cover that can be removed so that a fan can be put on it. There’s a screen on the inside to keep the dogs off of the fan. One end has a handle all the way across so that it can be moved by one person and wheels on the opposite end. There is a full size door on the end with wheels so that you can in and out pretty easy to get pups or clean it. There is a bumper rail around the bottom as well to help prevent pups getting mashed between the wall and the mother. There’s also a place to hang a heat lamp inside.
That's a sweet dog yard right there, and a really really nice whelping box too!