Purpose !
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The aim of the following pages is to describe a "relatively easy" way 
to form sleeve inserts for the commonly available 21.5 mm white PVC tubing.

This Tubing is often used as launch tubes due to its  perfect fit in a water bottle neck.
Unfortunately for most of the world (apart from the USA).
There is no commercially available PVC tubes fitting tightly, or slightly loose inside it. 

Therefore i devised a method suiting an average "handyman" to do exactly just that.
By choosing a different sized tubing. Using a suitable "mandrel" And a couple simple power tools. 

Supplies:
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Mandrel: round metal curtain rod (The cheap one covered with the white PVC sheat.)
 +- 16.5 mm covered with its sheath ("+-" Because it's not exactly round.)
 +- 16.0 mm Unsheathed.

Tubing: Clipsal 20 x 12 PVC Oval electrical conduit (See picture and ref later)

Tools: 100 mm angle grinder with thin metal cutting disk.
       Heat gun. 
    
Now  grease your mouse, sit back, and start clicking !