Doing things for your own use, where you are taking all the risks, is perfectly fine. As soon as you try to sell it to me, you have a duty of care. You are not

Doing things for your own use, where you are taking all the risks, is perfectly fine. As soon as you try to sell it to me, you have a duty of care. You are not meeting that duty of care with this ignorant and reckless way of working.