Spool shaft for FormFutura & ColorFabb Filament for Mark Wheadon's big spool holder

This is a shaft for the big spool holder of Mark Wheadon
http://www.thingiverse.com/thing:761893

I designed it to use it with FormFutura filament spools.
Update 2016-01-04: I mentioned that it also fits to ColorFabb's filament!

The outer diameter is 52mm.
The length is 100mm. (v1 - v3)
The length is 115mm. (v4)
The large diameter where the spool is placed is about 65mm in length.

There are 4 versions of it.
- v1 was the first design
- v2 was optimized regarding t