
I used a traditional open tray wooden whelping box for my first 2 litters.
Then I bought a Puppy playpen with a Plastic tray base.
I still use the base, but with Croft puppy panels (though still have the original plastic coated puppy panels).
I join the panels with zip ties (more reliable than the clips) in the base with a gated one at the front, and one across the top
I then attach cardoard round the outside.
A blanket over the top makes a cosy cave, and alliws for regulating light/visibility.
I use a heat pad for added warmth initially.
Once pups are 3 weeks I dispensed with the waterproof base and extended it with more panels on tiled kitchen floor.