I spent the morning making up some flat pack supers. Please ignore the Battery... it is nothing to do with this!
First I drilled some holes for the screws. I don't nail them
I then rough assemble them with my waterproof glue
Position the inset sides using some top bars from frames
Tap the "handles" into place using a mallet
Then screw the rebated sides on to the ends and like wise screw the ends to the handles
Because the wood is all pre cut and machined it tends to pull itself square.
I then wipe it all over with a damp cloth to remove the excess glue.
As soon as the glue is all set and cured I will give them a dose of boiled linseed oil to weather proof them.