Abstract: The invention refers to a spool (10) for supporting a filament (90), comprising a first flange (21), a second flange (22) and a connector (30), the connector (30) connecting the first flange (21) and the second flange (22) and defining a winding surface (40) for winding the filament (90) about a winding axis (X). Thereat, a plurality of openings (33) is provided in the connector (30), the openings (33) running in radial direction (R). The invention also refers to a filament spool (80), comprising a spool (10) according to the invention and a filament (90), in particular a thermoplastic filament (90) for use in a 3D printer, the filament (90) being winded thereon.