Generates one adapter - print two of it to be symmetric

Thanks to Emanresu.
Original design and code by emanresu (http://www.thingiverse.com/Emanresu)
Customizable Spool Adapter http://www.thingiverse.com/thing:82800

I optimzed/reduced the used Material on the bigger diameter.

I used it to adapt the Axle of
Spool Holder for small build plates
http://www.thingiverse.com/thing:224853
to
Spool for Laywoo-D3 3mm and 1.75mm
http://www.thingiverse.com/thing:39564

custom_spool_axle_adapter_19_27_32_20_8.stl ist the Version with Parameters

/* [Diameter] */

// diameter of the axle hole [mm]
axle_hole_diameter = 19;

// diameter of spool hole [mm]
spool_hole_diameter = 27;

// diameter of spool hole [mm]
adapter_diameter = spool_hole_diameter + 5;

/* [Lengts] */

// length of spacer [mm] (useful for centering a spool)
spacer_length = 20;

// distance bearing sticks into spool hole [mm]
spool_hole_depth = 8;