Puppies play hard but sleep long hours. A crate represents a den-like safe place. It also helps in house training. Place your crate where pup can see you - beside your bed at night is ideal. This gives the feeling he is not alone.
Dogs are pack and social animals.
They do not do well in isolation. The metal folding crates are best. Your dog will use it the rest of it's life plus you can fold it up and take your pup with you on vacations. Remember-the crate is a training aid. Pups can not stay in it for extended periods of time.