We've updated the rear axle in the version 3. The instructions are included with the fittings sold at www.ideas2cycles.com
The BB drop is something the designer of the frame knows. We use BB height in our designs and from that the BB drop can be calculated.
The center plane is 58.5 mm from the surface of the profile. It could get a little cramp when brazing the back side of the frame so be aware of that. You could move the center plane outwards to get more room.
Of course any profile could be used but it requires some rethinking of the dimensions. Any 45x45 profile will work.
Great! Yeah, we have changed the dummy axle for version 3 at http://ideas2cycles.com/products/the-jig/
The reading depends on your rear spacing (for example 135 mm), drop out thickness (for example 6 mm) and the location of your center plane (for example 58 mm). So the reading on my caliper is irrelevant. You can use the spreadsheet to calculate what it should say in your specific case. All of this is simplified in version 3 of the jig at http://ideas2cycles.com/products/the-jig/
You can of course design a similar jig with any profile but this instructable and the machined parts are based on 45x45 profile and Minitec fasteners. You can ask compatibility with other profiles at http://ideas2cycles.com/products/the-jig/
Yes, they are all 1000 mm long.
One of the profiles has a 10 mm hole in it, which makes it different from the rest of the profiles.
Nice! Looks good.
Carbon fiber bicycle fork