Holder for original M3D filament bobbins. Consists of two parts that can be pressed together and secured with glue or a screw. Placement of the spool is similar to ilikesanta's design; it takes some space, but the filament path is optimized for lowest friction and avoids collisions with any moving parts.
Printed with my M3D using clear PLA on blue tape, medium quality and high fill (5mm cross hatch). Raft and support material turned off. To fit bobby1 turn it 20 deg around Z-axis. Print time is 7h for bobby1 and 3h for bobby2.