This adaptor plate was designed for the Venev Orion 6x1 sharpening stone but may hold others. It uses the Shapton Kuromaku base, which is a great size and doesn't slide around. If you're into knife sharpening, you've probably got one already.
See also my holder for Atoma diamond plates: https://www.printables.com/model/909763-atoma-diamond-plate-holder-for-shapton-kuromaku-ba
The author marked this model as their own original creation.