I had bought a B&M rear dynamo light, which had an integrated reflector and was designed to to on the back of a rear rack. I rarely use a rear rack so I got a new light and knocked up this bracket.
I guess I can make you one, but you just need some brass tube, a hacksaw a hammer (or vice) a drill and a file.
I just flattened a section and then another at right angles to the first. Drill holes to mount light, bend to the required angle and file the ends to a round shape.
I had bought a B&M rear dynamo light, which had an integrated reflector and was designed to to on the back of a rear rack. I rarely use a rear rack so I got a new light and knocked up this bracket.