The floor boards or foot rest of the BMW R12 came in two different types for the motorcycle during its production run. In the early years of production they had aluminum foot boards. In the later years or Military production they eliminated the front foot boards and added pegs only and made the rear foot boards in sheet metal. Below is an example of all the drivers foot boards and pegs.
Here is a rear foot rest for the passenger in stamped sheet metal (Military).
The rear passenger foot rest (military).
Here is the underside of the Military foot rest. If you look closely you will see the nuts are black step nuts.
Next is the civilian rear foot boards. These are from a cast aluminum and just a little different than the military counter part. If you notice the civil version have two extra holes in them. This allows for movement of the foot rubber. I honestly believe the foot board is more comfortable without the rubber.
The front drivers foot board is much larger than the rear and much more comfortable. It has plenty of room for the drivers feet and makes driving comfortable. The front of the board is curved upwards to deflect mud and wind.
On the Military BMW R12 you had drivers pegs. Lots of photos exist with Military BMW R12 motorcycles with civilian floor boards. But in the 1941 BMW R12 parts book ( D605/4) these drivers pegs are in there. These are original BMW R12 drivers pegs below.