This is essentially an ordinary beachball with foam "detonators" glued around the outside, and painted black, in order to resemble a WWI era contact triggered naval mine. You should under no circumstances leave these lying around in rivers, streams, harbors or sea-lanes to excite gullible members of the public. Remember the meta-rules of KAOS:

1. Do nothing that will cause harm to another person.
2. Do nothing that will get the K.A.O.S. club banned from anywhere.
3. Have fun.

These are intended to be used to "mine" the river Leith during the annual Leith Bicycle race at the University of Otago. Afterwards we'll probably find an excuse to use them in Pacifist Warfare

You should construct the mine over the course of 3 days, given that you will need to glue it twice and paint it once, and you should leave it to dry overnight each time. You will need the following ingredients:

• An ordinary vinyl beachball, at least 60cm in diameter
• A sheet of closed cell foam at least 1cm thick (e.g. a sleeping-roll)
• A length of soft foam tube (pipe insulation), I'm using 10mm inner diameter tube with a 9mm wall (outer diameter 28mm)
• A tube of urethane glue (selleys, not uhu and not any kind of superglue); this is necessary in order to glue foam to a flexible vinyl surface
• A can of black spray-paint (spray-kote brand works well on vinyl)
• A short length of garden hose
• Electrical tape, to hold the foam to the beachball while the glues sets (note, electrical tape is the best for sticking to and pealing off vinyl)
• A short length of plastic chain to anchor the mine (optional)

You can buy the beachball and foam tube from Para, and the paint, glue and foam-pad from the Warehouse. You'll probably have to go to a hardware store for the plastic chain.

1. Inflate the beach ball as far as you can
2. Cut 13 foam rings out of the sleeping roll. The hole in the center of each should be the size of the foam tube, so that it fits into it tightly. The ring should be about the diameter of a coffee cup.
3. Cut out a 14th disk (the anchor-point A), and cut 2 holes into it near the edges for the ends of the short length of garden hose; this should likewise fit into these holes tightly.
4. Take 6 of the rings and glue them onto the beachball; 1 top, 1 bottom, and 4 around the circumference (see figure 1). The easiest way to do this is to mark 2 "poles" on the ball, and get somebody to turn the ball around them while somebody else marks the "equator" with a marker pen; then you just need to mark 4 equidistant points around the "equator". Make sure not to cover the beachball's inflation valve! This should probably be about 5 inches from the outside of one of the rings, as this way you're unlikely to cover it later. You will want to tape the rings to the beachball to allow the glue to set without the rings sliding around or lifting; use plenty of electrical tape for this.
5. Divide the beachball into 8 triangles by connecting the rings on the surface (you may want to use a marker pen for this). Glue the remaining 8 rings in the center of each triangle (see figure 2). Again you will need to tape these to the beachball while the glue sets. It doesn't really matter at which stage you glue on the anchor disc, so long as you do.
6. Leave the glue to dry overnight
7. Cut the foam tube into short lengths, and glue it into the rings, applying the glue to the end of the tube, and around around the inside edge of the rings. Do the same thing with both ends of your short segment of garden hose; this completes the anchor point (A) (see figure 3). You may also want to tape these down while the glue sets.
8. Leave the glue to dry overnight again
9. Wash off any adhesive tape and hang the mine by it's anchor point (A) in an area suitable for painting. Spray-paint the whole mine.
10. Leave the paint to dry overnight

Your Beachball Naval Mine is now complete! Use the plastic chain to anchor it to something like half a brick in an old sock when laying it in a river or stream, or for a more surreal effect, hang it from a tree! If you are floating the mine, you might find it effective to fill it with air and water in order to get it to float lower in the water. Deflate the mine for storage.

Or you could use it for this.