For a smaller but decorative version check out https://makerworld.com/en/models/166276

Have you ever seen an executive's office without one? Then why should you go without!? The classic desk toy and demonstration of conservation of momentum and physics is available to print without any extra hardware! In the office these make the perfect tool to brainstorm, refocus, unwind and meditate, or simply start a conversation. For the classroom these are an essential demonstration in classical mechanics that no physics teacher should be without. For everyone else, I mean just look at this you know you want to play with it…

Feel free to remix if you have ideas for making one that works better! https://www.tinkercad.com/things/aKtssHNMYdr-big-ol-newtons-cradle

Changes from the original:

• Massive 250mm frame - Make use of that entire build plate
• Massive 40g (that's 10x!) / 40mm balls - More mass = More swing time
• Tighter connectors on the balls - Less lateral movement = More swing time
• Sturdier strings - Less lateral movement = More swing time
• Properly angled connectors on the strings - Less tension = Less friction on the axle

Printing

There are 3 plates: the balls, the frame, and the strings.

Balls - these are 100% infill. Make sure you tune your filament.

Frame - print this plate twice.

Strings - these are straightforward.

Assembly

Remove the brims

Snap the base together - it helps to lay one side on a table and press into it 1 snap at a time once everything is aligned.

Attach the strings to the balls

Attach the strings to the base

Swing!