Thesis statement:
The uses of medical 3D printing go beyond the unimaginable, helping in cases such as (list 1st reason it's beneficial), (list 2nd reason it's beneficial), (list 3rd reason it's beneficial). All of these reasons will definitely improve the medical field extensively.
Then you go on with your essay explaining why...
The 1st body paragraph being your first reason.
2nd
3rd
and so on.
