I'm fitting a long free-float handguard to a flat-top receiver and would like to fit a picatinny rail at the 12 o'clock position to extend the one on the receiver.  I don't want the one that clamps to the reciver rail, I'm trying to keep it as low as possible.  Maybe some picatinny bar-stock would work, just have to mill the radius in the bottom and screw/epoxy it in place.  Any ideas?  Les Baer offers a 4-way picatinny handguard but it would probably be expensive to mill away the 3 rails I don't want.  Any thoughts appreciated.