Enerjet by Aerotech, Astrobee D Build, Part 8, Launch Lug Rail

Sand a consistent angle from the smaller top plate, down the middle bar and onto the lower plate. 

Some of that "skin" left under the top plate will have to be lightly filed off.

Defining the rounded taper on the lower plate, I wrapped sandpaper around a 24mm engine casing.

Notice the pencil marks over the front end.

Rubbing some pencil gives you a high contrast surface while sanding. You can better see the width of the sanded edge.

 

Here's the completed piece ready for the gold paint.

 As it always seems to go - 

Paint shows imperfections. I had to sand some of the mold marks and rough leading edges. More gold paint to come.