At craft and design group we were given the chance to customize a t-shirt with fabric paint. I looked through some stencils in a box and a jellyfish caught my eye. It was tiny though, and a bit too intricate for my taste, so I designed an SVG version by typing numbers in a text editor defining circular arcs, with plenty of previewing in the browser to check that the curves were sweeping the right way. My first attempt wasn't so great, so I modified it to make the wibbles less severe.
Then the lovely Jo cut it out of card with her Silhouette Cameo machine and I had a stencil to use. Another group member made an eye-catching design by flicking paint from a brush with a stencil to mask his design, so I borrowed that technique. I stuck the stencil to the t-shirt with a glue stick so it wouldn't move, then applied paint of various colours:
The paint spray splodges are very fine, so it looks a bit fainter than I had imagined it, but it turned out ok.