By cutting the surface smooth.

被切削表面光滑平整。

youdao

He wanted to rasp the surface smooth.

他想把表面锉平。

youdao

Now you have to pull it to make the surface smooth like that.

现在你再把它推过去，让表面像那边一样的光滑。

youdao

In an effort to mimic the soft exterior of a real bed, Mr. Fischer coated one of the bed sculptures with white paint but then interrupted the smooth surface by pouring a pile of real concrete over it, weighing down one side of the sculpture's surface.

WSJ: Urs Fischer's Beds & Problem Paintings Show in Beverly Hills

In 1969 he created a new curved ice ax, the Piolet, which gave climbers better purchase, say, on the smooth surface of a frozen waterfall.

FORBES: The World According to Yvon

They clear and fill the holes, then use a roller or whacker to smooth the surface.

BBC: Jetpatchers at work