When the sun goes down in the winter, Sarah Maguire sends her husband Ryan outside to their Milton backyard skating rink to perform what she calls “ice maintenance.”

With their yellow lab, Sully, by his side and a beer in hand, Ryan brings their “mini Zamboni” — constructed out of a mop with a hose attached — outside to smooth on a fresh coat of ice by spraying water onto it to freeze overnight.

From left, Ryan Maguire and his children Liam, 10, and Mollie, 8, unroll plastic while preparing their backyard rink at the family’s home in Milton on Dec. 9. The Maguires are among a growing number of families building backyard rinks each winter. – Erin Clark/Globe Staff

“He’s crazy about the ice maintenance. Friends of ours are always calling each other for tips and tricks. ‘How’s your ice

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