For this Barn Door, you need three 30cm (12") bamboo BBQ skewers. The photo shows them laid over the sail, before being snipped to length with scissors.
Wait for the glue to dry. Maybe start another one of these kites, so you can fly them together in a train later on!
At this point, you've finished making the 1-Skewer Barn Door!
This design seems to need a little tail-weight for stability, so stick a couple of strips of sticky tape along the whole length of the trailing edge. That is, the edge of the sail between the lower tips of the 2 diagonal spars.
To attach the flying line, just Lark's Head the flying line to the bridle line as in the photo.
Now for the cool bit... If you have made 2 or more kites, each attached to their own flying line, you can hitch them together in a train. Just put a fair-sized Loop Knot into both ends of each flying line, and then it's easy to attach and un-attach the kites.