Step 10: More on the bowling ball bowl from step 5...and a link to a great Instructable!
In a nutshell, you simply choose a bowl that is larger in circumference than your bowling ball.
Fill the bowl half to three quarters full of concrete, submerge the ball in and give it a squish.
Allow it to dry.
Remove the ball, remove the bowl and there you have it. :-)
Want more? You should definitely check out Creativeman's Bowling Ball project!
Great job, Creativeman!