Aluminum bowl

step one: draw the radius on the metal sheet.

step two: use hammer begin to hack the circular metal sheet from the outer circle, while hacking the metal, kept rotating the metal.

step  three:  after finishing the step two, use the English whale smooth the surface.(after that  I have used some sand paper to make the surface more smooth. 

CONCLUSION:

key points of making a bowl:

1.when making a curved surface like a bowl kept the same strength to beat the metal each time and rotate it at the same frequency.

2.use sandpaper to polish the surface would makes it looks much better.

3.While choosing the radius of English while, choose the one with a curved edge, otherwise, it would produce plenty of linear markes on the bowl.