The carvers were given three days to sculpt a 3m-cubed (106ft-cubed) block of snow using only tools, more snow and water.
Teams were tasked with illustrating the theme of fair play and Unwin said the sculpture she designed was “ridiculously complicated”.
She said: “It was so difficult to work it out but we did actually do it.
“At about four o’clock on the last day, I was sort of thinking: ‘I don’t know if it’s going to work,’ but it did.
“It was a bit rough around the edges, but it was snowing quite a bit, so it covered up the mistakes.”
She added: “We came second which is just very exciting because there were some really good ones.”