SLICE & TWIST STREPTOHEDRONS ARE FUN TO PLAY WITH AND OPEN UP ALL KINDS OF POSSIBILITIES
(but you need a bit of understanding of the concept behind them)
The simplest streptohedron is what I think of as an Equilatecon. Start with an equilateral triangle (all three sides the same length) - and rotate it to create a turned equilateral cone whose diameter is the same as the legnth of the side of the cone. If you split that equilateral cone in half, rotate one half 120 degrees and stick the two halves back together, you get the simplest "streptohedron" - an Equilatecon.
The use of a "glued paper joint" - to stick the two piece of wood for the blank together - makes separating the two halves so much easier than having to saw them apart (and there's no kerf width to have to account for in the turning).. Turn the two part blank to the desired shape and "split" it in half. You do have to keep in mind that you're blank will have a weak plane in it - at the paper joint - so you have to be carefull that your drive and tail centers don't split the joint open if you overtighten things.
The key to turning an Equllatecon is to have the "sides" of the cone equal to the diameter of the cone. You don't HAVE TO be exact with the dimensions, you can always do a little sanding to deal with slight mismatches and almost no one will ever know.
Maybe these illustatrations will make things clearer. If you click on the image, you can download the SketchUp file of these virtual 3D models and, with Google's FREE SketchUp or SketchUp Viewer, get to know and understand how this Streptohedron idea works.
(Equilatecon.skp 240K download size)