Dan Jefferson wrote:
Wanted to flatten it to make a small stool or table.


In that case, why not sand it?

You would be amazed what some 24 grit discs on a right angle sander can
achieve.

(BTW, it's a basic boat building tool.)

Use a straight edge as a batten, to find the high spots as you go.

When you get close, switch to a fairing board.

Since this is a relatively small piece, you won't need a big fairing board.

Mount some 24 grit flooring paper on a wooden concrete float with some
rubber cement and you are off and running with a one hand fairing board
about 3"-4" wide, 18" long.

Lew