30mm ball
thingiverse
A 30mm ball for the Newton's Cradle model found here: https://www.thingiverse.com/thing:4797803
Download Model from thingiverse
With this file you will be able to print 30mm ball with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on 30mm ball.