Do I need to register a business?

Hello :)

Long story short: Yes, you have to register your activity here.
Whether you do so as a business, a freelancer, or something similar is up to you.

Personally, I registered a business. At first, it feels like a huge amount of paperwork, but it’s really not a big deal. You could call your local municipality and ask them to explain the process. For the tax forms, I had a really helpful contact person who walked me through the entire form.
You’ll then need to file a simplified income statement (EÜR) with your tax return. If you have a knack for that sort of thing, you can do it yourself. Otherwise, have a tax advisor handle it :)
There are also a few freelancers here. Maybe someone else can help you out as well.

  Unfortunately, you can’t test the waters by selling the patterns. That’s just the risk you take when you decide to do this :)

One more quick note: Very few people can make a living off the income from selling patterns. There are a few “big names” who do this full-time... but the vast majority just earn a little extra pocket money on the side.
  If you put your heart into it and manage to cater to your customers’ tastes, you can definitely be successful… But it’s not as easy as many people think. There have been quite a few who started here and threw in the towel after a short time.
  I don’t mean to discourage you—I just want to say: As with everything in life, nothing comes for free ;)

I wish you all the best and look forward to browsing your shop soon.