I constructed the handle retaining bolts so as to have heads like the ones on the Browning T-152.

T-152 Detail

I like the look of the spanner bolts on T-152. I didn't own a metal lathe when took on this project, so I went to my trusty hardware store and bought some 3/8" stove bolts ("A", at left). 1/2" bolts will give a bigger head if you want.
B) I chucked them upside down in my drill press and, while the bolt was turning, filed off the grade numbers and galvanized surface so they would take bluing or Parkerizing.
C) I turned them right side up and center punched, then drilled a 13/64" hole for a 1/4" - 20 tap. There is a convenient square shoulder on a stove bolt that holds it nicely while tapping. After tapping the holes I cut the heads off the shanks.
D) I threaded one end of a 1/4" rod (you can save time and buy threaded rod) and then I screwed the heads on upside down and clamped them in a vise in preparation for drilling the small tightening holes. For a spacer I used the bushing I later used for the trigger roller. Once the hole was started I removed the spacer. (I tried drilling from the arched top of the bolts with predictable messy results. Drill from the back)
    I threaded my own rod because I could, but dies are expensive. Threaded rod is cheap and will work fine. To get the smooth top bolt I simply screwed on a bolt head about a half turn shy of flush and then welded it in place. I chucked it up again and filed as in "B", above, left.
    The bottom heads I left open. I drilled a 1/4" hole in the top bracket so the rod would pass through, but I drilled a 13/64" hole in the bottom bracket and tapped it 1/4" X 20. That way the nut is a lock nut, and keeps the whole bolt assembly from turning so the top holes stay neatly in line.

Here (left) is a variation. A long 1/2" carriage bolt (I use a 12" bolt to get the long shoulder needed) is altered by removing the square shoulder with a metal lathe, cutting the bolt to length, then drilling and tapping a 1/4" hole in the bottom. A second, short carriage bolt is turned to 1/4" and threaded. This drawing shows the resin handle with an Allen screw keeping the handle from rotating. To see more details on making this type of bolt, click here.

This is the assembly used on the ANM2, but I have used my own dimensions and made the tubes from 5/8" steel rod. I drilled and tapped lengths rod, then milled a slot for 3/16" keystock. The trusshead drilled spanner bolts were turned from 1/2" carriage bolts (drawing below).

Rather than thread the area where the square shoulder was removed, I turn the shank down so as not to interfere with the tube threads.

Here is a drawing of the spanner bolts if you would like to take the extra time to thread the shank.

This is easy to make, and the best design, as it allows for variations in hole centers. This is the wrench I settled on.
I made a simple spanner wrench by threading the shank and tapped the handle & base. I used two short sections of a jeweler's file handle for the pins. Then I welded the whole thing for good measure.
I was looking at a golf shoe cleat wrench one day and realized it was the perfect design for a spanner bolt wrench. The pins are removable and replaceable. Too bad the cleat wrench is too small. I made this one from stuff laying around my shop. The overall length is 5".

GI spanner wrench.