I support the site policy to ask and answer questions in the public forum. I am confident enough in my answers to accept public scrutiny. Public questions and answers may help others. In this case, some would be breeders could get a glimpse of what all is involved in whelping and caring for puppies. It is not easy to do right.
From a PM:

Originally Posted by
bruisersmom
So the vet did an ultrasound and there appears to be 3 pups and we guess that they are due in about 4 weeks. I have been doing lots of reading and am wondering about a whelping box. I really don't see the need to buy something expensive since this is the only puppies we will let her have, do you have any suggestions?
And thank you for your help as this was a complete surprise.
I don't have too much experience whelping puppies. My friends have huge easy to clean fiberglass boxes. The box has sort of a shelf running around the outside so that the puppies can fit under and the mother can't pin them against the edge or lay on them. I am glad you doing some reading whether it was my suggestion, or your own good sense.
For a one time only, I know many times a cardboard box suffices. In fact that was what my friends used when our Aster was born. Make sure it is big enough that she can keep the puppies at one end, and take them to the other end to eliminate. This is extremely important. New born puppies can't eliminate themselves. Given a chance, the mother will pick up a whining puppy, carry it away from the nest, set it down, and stimulate it by licking its back. It then eliminates and quits whining. She carries it back and gets the next. If you don't promptly remove bowel movements, she will eat them. For those having trouble housebreaking puppies and with them fouling their crate, thank the breeder for keeping the mother and litter crammed together.
Mark the puppies if you need to so you can keep track of them. With only 3 and maybe different colors, you may not need to. With say 10 black lab puppies, you must do something, different colored collars or shaved patches in different spots.
As I said, keep in touch with the vet. Who knows what all she may have been bred by. It is possible the puppies may be too large for her to deliver and may need Cesarean. The vet can do another ultra sound later. I have to look at the contrast between you who are doing your best to give her the care she needs, and whoever let her get pregnant. May God bless you.