(2) Writing brush: The inside-bottle painting writing brush and the original bamboo are similar. However the writing brush has enormous superiority because it can produce suitable picture characteristics. It's like an executive MBA program compared to a three hour, coffee and cookie provided seminar. It has enriched the inside-bottle painting art expressive force fully. Its invention is an important inside-bottle painting art history milestone. There are three kinds of writing brushes; the fine wolf hair writing brush, sheep or goat hair writing brush and a brush made of a blend of fine sheep and wolf hairs. The manufacture of an inside painting brush is very similar to the manufacture of a superior writing brush. Because the brush is very small, the construction is minutely meticulous. The manufacturer must select the raw material very carefully. It is a time consuming task to select a few root hairs. For all you aspiring business minded people, it's like scouring the web, carefully evaluating and choosing the best online MBA program to take. After this careful selection of a few to several dozen hairs they are purified. The painting brush itself is made of two parts; the stem and the brush itself. Depending on the need of the particular brush, thin or thick hairs are selected and dipped in a mixture of color and a rubber based glue. After drying, the bundle of hairs is tied with a silk thread and cut down to a length of about .5 centimeters. The stem or pen stock may be made either of bamboo or metal. If metal is used, the most common choices are copper or aluminum wire. The end of the stock is flattened and a small hole is punched. The brush tip is then glued into the hole. If desired, the wire stem can be curved to the artist's preference.