911R Oil Tank Hole

[CleverCog]

Hello.

In the midst of a fair amount of bodywork on a 1968 912 turning into my version of a 911R clone--which I am calling a 911c.

I am curious how folks have executed getting the oil tank hole in the car with the nice return on it.

I've heard things like:

1. Popping the hole in and fabricating the return with welding rod or similar
2. Make the hole and return off the car and then welding that on
3. I've seen one picture where it looks like someone made a tool that looks like a punch and flare tool set (https://www.mittlerbros.com/4-punch-flare-tool.html)

Any suggestions? Anyone have any experience with this?