This is a very basic, very easy plan for a piece of line junk. Although there are quite a few "line-junk" related plans on the internet, they are all quite difficult and cumbersome. This should take you about 20 minutes or less to complete.
4 x 15cm x 15cm ripstop nylon (this should be adequate to make 2 spinners with 4 different colours). Browse around in your leftovers bag, you are bound to have plenty there!
1 x 62cm x 2cm ripstop (double up for 2 spinners)
1 x 62cm packaging strapping (or whatever they call the strips that they put around boxes) (double up for 2 spinners)
a thin (2-3mm) long piece of ripstop for the tail
1 fishing swivel per spinner
80-90cm thin line
Hot cut the 4 triangles from different colours of ripstop
Stitch the triangles to each other at the 1cm ends. Do not close the circle by stitching the last triangle to the first one yet
Mouth of the spinner
Fold the 62cm strip of ripstop double in its length and stitch to the top of the triangles as shown in the picture above.
The seam should be very small (1mm or so) and should come on the inside of the spinner.
Close the spinner by stitching the last and the first triangle to each other. Be careful not to sew into the tape on top of the triangles.
Insert the packaging strapping into the tape and cut off slightly shorter than the length of the ripstop tape.
Fold the spinner inside out and sew the 2 sides of the tape onto each other (the stitching should go through the packaging strapping).
Fold both ends of the tape to one side and stitch to the tape again.
The other ends of the triangles can be attached in different ways, depending on your preference.
Either "catch" the tip of each triangle and the start of the tail with the sewing machine needle and finish off or simply glue them together (I would use Bostik Clear or Pattex).
Cut the line in 2 pieces of around 40cm each.
Pierce 4 holes (the easiest is to locate the holes above the 1cm side of each triangle) in the tape (but below the strapping) and feed the line through.
Make a small overhand knot at each of the 4 ends.
Knot the lines with the knot shown above. The knot looks more dificult than it is. Remember: around the line twice, then through the loop and pull the line until the overhand knot stops against the loop.
Attach the swivel by using a small loop and a larkshead.
The triangles can be smaller/larger as you wish, but you may want to increase the number of triangles to above 4 if you increase the size much more than 15cm.
Attach a few spinners to each other for added effect.
Attach spinners to short pieces of string, which are in turn attached to a 15cm stick for children to run around with.
THAT's IT! TO READ THE INSTRUCTIONS WILL TAKE MORE TIME THAN BUILDING A SPINNER!