12mm Wheel Hex bearing adapter and center cap

Trailer built, but no wheels or so yet.
Had 4mm carbon rod for wheel axle, and still needed to get the wheels installed, made a 12mm hex that fits a ball bearing 4x10x4mm, we used a flanged bearing.

The fit is tight, I needed to sand/file the hole abit, otherwise the part broke.
But I got it, and it´s now on my wifes trailer, works great.

And the center cap is a tight fit also, you can use a 4mm drillbit to open it up a bit.