By mounting an installations tube in the box, I can feed the filament direct from the box to my printer. That's very convenient!
My spool have all about 20 cm / 8 inch diameter but there is some space left to the wall, so 21.5 cm / 8.5 inch should also fit fine.
It is fast and easy to print. It is very easy to assemble. A drilling jig is also included.
The STL files are for M4 screw and nuts, but as it is customizable you can configure it also for inch parts, other tube/pipe or boxes.
I recommend also this things:
- [Spacer](http://www.thingiverse.com/thing:728531) to hold the spools apart (I'm using simple_spacer_32x5.stl and simple_spacer_32x10.stl )
- the [Spool Adapter](http://www.thingiverse.com/thing:735213) for perfect fitting of different spools
- a [Filament Clip](http://www.thingiverse.com/search?q=Filament+Clip)
For sealing your boxes, you may find this things useful to control humidity:
- [SAMLA Lid Clips](https://www.thingiverse.com/thing:393890)
- [Angled Dry Box Feeder or 1.75mm Filament Feeder for Dry Box](http://www.thingiverse.com/thing:878919)
- [Filament Wallsupport](http://www.thingiverse.com/thing:970574)