You will need to print two of these for a complete Yoyo, its a very basic design.

The dimensions if the Yoyo are 50mm round, 10mm high and a 6mm hole, I also use this print as a quick printer test.

Will require a 5x25 mm dowel as an axle.

For stringing and details I used the following web page as a reference (not affiliated):

http://www.yoyoguy.com/info/yoyo/#:~:text=String%20length,Trim%20off%20the%20excess%20string.