It's built with something called a buttressed core: you have a strong centresection with legs that buttress it all the way up.
它的建造依赖这一个支撑核心：你有一个坚强的核心部分来保证整个塔是直的。
2
To begin, lie the shirt out on a table and then draw an imaginary line half-way down the shirt and another half-way between the outside edge and the centresection.
首先，把衬衫平整地摊在桌子上，在衬衫中间划一道想象中的线，再在外围和中间区的中线位置再画一条线。
3
For tubular structures, such as blood vessels, the hydrogel is printed in the centre and around the outside of the ring of each cross-section before the cells are added.