To make a Christmas tree collar, you'll need some basic supplies such as a large cardboard box, some wrapping paper, scissors, glue, and tape. First, cut off the top and bottom of the box so that it's flat. Then, cut the remaining sides of the box to create a ring. Next, wrap the box with the wrapping paper, using tape and glue to secure it in place. Finally, place the tree collar around the base of your tree and enjoy your festive decor!