This model is based on Johannesbehr mini spool http://www.thingiverse.com/thing:129173 and esun spool combine what I like about each and voila get the spool the way I like to use with my loose filament. From Johannesbehr design I use the dimension and the guard idea from esun spool I use the screw to attach it together that way avoid me designing two different parts and also to glue it. The spool hub is 32mm which fit nice in my printer. If you print it keep in mind that this is a small spool that only hold a max of 50g of filament.
UPDATE files have 1mm thickness in the walls

Required two M3 screws and nuts non printable
Printable
Print two pieces of spool half and one guard. The holes may need to
clean up depend in setting use to printed. Fit the screws in one of the
half's and the nuts in the other half then put the guard in between
both half and tight them together.