Here’s a simple Celtic knot you can make using only paper and scissors.
Download and print 1-14-15 template. There is one template in the file. You will need to print it twice:
Cut out the two loops (cut out the doughnut holes in the middle, too).
Cut open the loops along the dotted line.
The lines across the loops indicate where another loop crosses over it.
Arrange the two loops to look like this: