Works with makerworld clock.

Here is the a 3d printable concrete form that accompany this instructables: https://www.instructables.com/DIY-CONCRETE-Clock/

It is quite simple, print alll the parts.

1. Assemble the form.
2. Make a small dowel to go in the middle.
3. Ensure that it is the right length so that the top of the form is flush.
4. Pour the concrete.
5. Wait a minimum of 48 hours.
6. Break the concrete out of the form.

When you print the form make sure that it is printed very weakly so that you can properly and easily break it out of the form.