Additive Manufacturing (3D Printing) is the processes used to synthesize a 3D object under I have an idea concerning prevention of allergic diseases. This idea of mine was deduced from the fact that few carriers of parasites suffer from allergic diseases. I was helped by the hypothetical theory of the late Dr. Sohmei Kojima; Few parasite-carriers suffer from allergic diseases because anti-parasite antibodies preoccupy the receptors of anti-allergen antibodies. My method of prevention of allergic diseases is to control the frequency of your taking bath and/or shower. In other words, you’d better keep your body adequately dirty. In more detail, dirtier bodies have more number of miscellaneous microorganisms that are not pathogenic. However, they can let your bodies make their antibodies, which are capable of preventing anti-allergen antibodies from combining to the receptors. In conclusion, my method of prevention of allergic diseases is to reduce the frequency of your taking bath or shower. Practically, to take hot bathes 1~2 times a week will be sufficient. I admit that this idea of mine appears pretty ridiculous. But I also have positive results, i.e., evidence. The evidence I can show you comes from my own experience. I acquired coldness-allergy after working overnight in a cold room of 2 degrees centigrade in order to purify Thiamine pyrophosphokinase from Baker’s yeast 49 years ago. My coldness-allergy persisted till a few years ago. I reduced the frequency of hot bath to once in 4~5 days a couple of years ago. Today, my coldness-allergy is almost gone. Obviously, relevancy of this idea of mine is supported by the fact that allergic diseases are seldom seen in developing countries. In conclusion, this idea of mine is worth examining, at least.