I purchased a few sheets of Christmasy scrapbook paper at Hobby Lobby. I had to buy the 12X12 inch size, but I cut it down to 8 1/2 by 11-inch since that is the size called for in the directions.
After you have the 8 1/2 by 11 inch paper, you fold it into thirds lengthwise. I have tried to show that in the photo below.
Then you make alternating cuts along the folds of each side as shown in the photo below. I drew the lines with a pencil to help my son know where to cut, but when I made one by myself, I just did it without the lines and it turned out fine. The key is to cut close to the fold (about 1/2 inch from it) but not through the fold.
Below you can see my son cutting on the lines. I had him cut all the lines from one side first, then we turned the paper and he cut the other side. Afterwards, I cut a few of the lines a little longer where he didn't cut all the way to the end of the line.
Next is the fun part. Unfold your paper carefully. At first it will just look like a piece of paper with lots of slits in it!
But when you pull gently on the ends, you can stretch it out like a spring and see the pretty pattern. We looped one end to a branch near the top of our tree and stretched it out, then looped the bottom end onto a lower branch.
Although my youngest son hasn't made one of these yet, I think he does have the cutting skills needed to do it. So, I think you could try this with children as young as 3, depending upon how well they can cut. I would probably help him hold the paper as he cuts. Also, go ahead and try this even if you don't have "fancy" paper. I think this garland would look just as pretty with plain white printer paper.