I got my masts welded yesterday and could not resist to post some pictures. I know some are interested by this.
The tube were ordered as a group of 4 T38 builders from an aluminum canadian factory. Martin Hivon, member of WB, organized this, a thousand of thanks to him. Al is T6061, the best quality, 4mm thick for the walls.
It is strong, light (50 kg each), light maintenance and not expensive.