I can operate a welder. If there's an arc or oxy-acetylene setup lying around I can make sparks and produce globs of hot metal. But I can't guarantee that any two bits of metal that I work on will actually stay stuck together.
But these plans for a DIY bike trailer make me think I should trundle off to my local TAFE and take one of their basic welding courses. Simple, cheap, and sturdy - that's my kind of gear.
By the way, this design belongs to a charity mob in Britain called Re-cycle, whose mission is to collect up all the old clunkers cluttering up sheds across the UK, refurbish them and send them off to parts of the world where they'll have a huge positive impact on people's lives.
Bloody good work!