Steven, You could try utilizing hardboard. It is what the commercial shank makers use I think. You can aquire it at home depot, loews or any do it yourself store. In shoes it looks like pressed paper. at the store it looks brown and comes either smooth or perferated for hanging tools on in your garage.
Here is also an option to obtain it.
http://www.google.com/search?hl=en&q=hardboard%20panels&um=1&ie=UTF-8&tbo=u&tbm= shop&source=og&sa=N&tab=wf&biw=1878&bih=798 After you have cut the insole shape out, If you steam it a bit, by placeing it on a rack on a pan which has boiling water going, you can soften it slightly for making curves or filling in the arch area. while still damp, you can firm this up with glue while wet. tack and STRAP in place. Don't forget to strap! The tacks will tear the hard board when damp if you do not strap!
You still will need a steal shank reinforcment though.
I totally love alexanders' photo essay and method tho' It seems like a very quality construction. It is sort of a shaped clog like sole.
I think there is also mouldable plastic that podiatrist utilize for making orthotics with that you can use too. It is heat mouldable.
I wonder also if you want to utilize alexander's method of a wood shank if one could use 1/8 " hobby plywood purchased at the hobby store. It tends to be thicker and more stable than vaneer. Yet it can be shaped around long corners such as the arch area, and cut with a utility knife, Maybe an option????? Worth a try if veneer is to woobbly to work with.
Well that is my two cents, and ideas, for what they are worth.
Marlietta
Lastmakingschool.com
(Message edited by Last_maker on May 25, 2011)