
Originally Posted by
TopShelfKennels
I use a 4x4 box with the bumpers on the side, I also use a heat light and small heater in the winter. The pic is a litter I had last January and I live in New England. So it holds up to all types of weather.

Nice plan on the whole 
Three things worry me though:
1) It is very big, so some pups could straggle-off and get cold {although I see the heater, not sure how far it effects in cold weather if the pups straggles-off to a far corner};
2) It looks like the mama can jump out of there; and
3) The mama could bite and get electrocuted by the heater in the corner if she was a wild one.
Not criticism, just some thoughts. Also, if the dimensions were a little smaller (and if there was a top), the mama's body heat would warm the pups with no electrical heaters necessary.
That said, having a light source does help the mama do her job.
Jack