Those are about as solid as a hub gets and if I had a good supply of those they'd be my first choice for anything but serious racing applications... I know a machinist that is capable of fabricating these but they would run about $250.00 each and could also get built with cartridge bearings.

Some hubs have a spring clip as a seal... this is the rear hub on my '55 Lenton and is one of the smoothest hubs I have ever had the joy to use.