Well, this is prety simple model, so I created it for community. There are 2 versions of model - with hole (for keychain) and without it. Use it.
It's 10cm in diametr, so i recommend to scale it to 0.5 - 0.6
I don't think you will have any troubles in making this part. As i said earlier, print it in scale 0.4 - 0.6