Agreed. We did not and will not use a heat lamp indoors or out. Giving the chicks enough room last year was an ongoing engineering project until they could go outside.
We used a zippered dog pen last year. It was left over from when we had a dog recovering from surgery. She needed to be contained but also part of the household for 6 weeks.
Plastic, then cardboard on the (wood) floor were placed underneath, pine shavings inside. Set the whole thing under my...