Fits on 25mm Diameter Handlebar.
Print two of them
You need 8mm Woodsticks.
It holds soap pieces up to an height of 60mm without a problem. The length depend on your woodsticks. I used 130mm sticks.

Source for the Project is on Tinkercad
https://www.tinkercad.com/things/eVCfMJnsc4J-soapholder-v1
Take the piece that is labeled with SOAP03