I used the metal style puppy pen outside configured as a big rectangle with a big sheet of garden lattice and an old bed sheet all weighed down with a couple of smal window panes I use in the spring in my garden. It worked all spring as an excellent outdoor playpen for my chicks who grew and grew before we had our coop/run ready for them.I could also use them for runs for adult birds too. I could just put netting over the top...... the possibilities are endless!
It also made it easy to round them up when it was time to go inside to bed at night. No running all over the yard!