I use a Little Likes playpen to keep them in. It works great. I can make it into different shapes and sizes. square, triangle, octigon, t shape, lower r shape. I bought it at a yard sale for $10. I have another 1 I use outside for leaves in winter. and the rest of the year for little kids outside being we do not have a fensened in yard and the kids love to watch the older kids ride their bikes. I can even add both playpens together if neighbors come over.

I hope this helps.

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