HELP WANTED - how to make d shaped tubing?

[desbromilow]

hopefully someone here knows how to make D cross section tubing for bike frames.

trying to replace frame tubes in a vintage motorcycle which has D shaped tubes in the rear diamond...
am currently squashing circular tube in a press with shaped dies and packed sand in the inside, but the shape is still not right.

also looking for advice on bending the same tube in a tight radius with the centre of turn being on the flat side of the D


thanks,
Des