First get some regular masking tape, acrylic paint, parchment paper, stamps or other marking materials.
Stick the masking tape to the parchment paper as shown. Freezer paper does not work! The masking tape barely sticks to the parchment paper, but it sticks enough to paint it. My first sample was about 20 inches long and my second sample was 36 inches long. You can see the tape at the top of picture has not been painted yet.
I put a thin layer of acrylic paint on top first. After that I just started playing with dots and squiggles various patterns. I used some of that squiggly paint that comes out of a tiny hole.
Sometimes I used my heat tool to dry between layers of design.
I started another group, same materials all acrylic medium. Mostly I just used a paintbrush, but today I tried some stamps too.
These are the completed tapes from yesterday. I cut the parchment paper apart but kept the masking tape stuck on to it for later use. I tried rolling them up and putting a little rubber band around them but I didn't really like that so I unrolled them and I think I will keep them in a little looser roll up. They are a little more bulky than commercial washi tape, but they're prettier OMHO. Just sayin'