I drilled the hole first then cut as straight as I could with a metal cutting bandsaw. Next drew lines and took it the the belt sander to get the outside contours. I agree I like the small one best myself. I did shoe shine with some sandpaper to remove the burs after bandsawing the slot.
CW

Bigfoot,

One method I use for things like that is to put a thin piece of some softer metal like aluminum or brass between the two halves, clamp it tightly and solder it together with soft tin solder. Then I cut all but the last fraction of the distance and dress with a file. When just right, finish the cut. I try to use a shim that is about half the thickness of the saw balde I'll be suing to make the cut, so the saw follows the soster stuff and takes a thin kerf off each side.

This method works particularly well for me with a band saw or even a table saw. Any remnants of the tin solder can be stripped of chemically or with a bit of abrasive.

Rich