Loop the pin across the jump ring
Attach the buckle to the buckle strap:
Sew buckle strap to satchel flap
Sew flap to the back part of the satchel.
Sew the front and back parts, right side together.
Leave the opening unseen.
Turn inside out.
Sew the strap to the satchel.
Insert a folded strip of paper to give your satchel a square-ish shape.
1. Measure bigger than you estimate the satchel to be. You might end up with a teeny-tiny bag when you turn it inside out.
2. Everything can be accomplished through hand-stitching.
3. You might want to glue the flap to the bag once you’re done.