Kulitorum's Spool Holder

I needed a spool holder for my new printer, the DW-BOT (http://www.thingiverse.com/thing:375231) and I came up with this.
I use two different filaments, the ColorFabb filament that comes on a 50x200x55mm spool (Inner, outer, thickness) and some cheap Chinese filament that comes on a 30x150x89mm spool, and I wanted it to fit both. Also, I wanted to to be adaptable to future spools.
The idea is to screw the "Generic Screw" part to a panel in the printer, using the "Back" part as a inside off-l