WTB- Cromodora Daytona centre cap retainers

[xitsurf]

Hey Guys, looking to buy or ideas.

I bought the centre caps for my wheels (Cromodora Daytona) but no retainers. I know you can use a piece of flat plate but am looking for something a bit more substantial like the original - rear plug that held them on ( pictured_).
  The original was a plug-  like welch plug with two holes in it that was at rear of wheel .
Has anyone come up with a similar alternative . like a welch plug adaption etc.