hey there
answer to the question about doing full welds on the cheeks. i am only tack welding it together to try and keep it from distorting see as i had a few problems shaping the cheeks and getting them to stay in place etc.just going to fill any gaps with filler and sand down.as for welding aluminium correctly ,yeah it does take a fair amount of skill .any dirt or oil etc on the aluminium then it has a habit of collapsing in on you which aint much fun and as i said before has a tendency to pull and distort when fully welded.cheers paul