Agreed. But something still feels wrong with saying, "Nice, you spent 100 hours making something cool? I'd definitely pay $15 for a poor replica thereof."
Again, that is not what I said. What I meant was more along the lines of "You did a great work and I like both the drawing and its meaning. I would love to see that on a T-shirt, and if I were to make that T-shirt it would certainly give you credit for this."
I wouldn't feel like wearing a sweater like that for personal preferences, but I would like this idea to spread. You would definitely have a point if she designed and produced that as a T-shirt and now somebody else started making poor replicas, but hers is probably a unique specimen.
The idea of making a chart from prime numbers is definitely not copywrite-able. So go for it! I got the idea from a knitting magazine where someone described a blanket with a chart of prime numbers that fascinated a student who walked by who was in a remedial math class. They had a small picture of part of the blanket, and I couldn't figure out how their method worked, but I put those ideas into a sweater.
I have attempted to write a children's book about using this idea to make cyphers or just fun art. But I haven't tried to sell it yet. And I did a library program that went over very well with kids. Anyway, if anyone makes a t-shirt let me know -- I'd order one.
Though maybe I should do it -- I've got several colored charts already made from when I was working on my book. Give me some time, and I'll make a cafe press account....
I can see how it's easy to get hooked (sorry) on knitting and maths. You might start off doing visualisations of various sequences. Next, you wonder what happens if Fink and Mao's necktie analysis [1] is extended to an exhaustive analysis of knitting stitches, and end up with all sorts of multidimensional stuff. Finally that becomes too easy and you attempt to use a length of yarn to model the world line of a single electron [2] and accidentally win a Nobel Prize! :-)