Filament holder for the UM3 spools

My special designed filament holder are directly for the original ULTIMAKER 3 (UM3) spools.
Until now I use it for the 350g and 750g spools of 2.85mm filament (see pictures).

Advantages:
- Easy to clamp or unloose in the spool
- Best way of storing the filament spools
- Spools are better stackable
- No unraveling of the filament
- End of filament doesn't have to be fixed in the small hole and the danger of breaking filament

I'm looking forward to your feedback and especially if it w