Prusa i3 Dual/Single Spool Upgrade

While the factory Prusa i3 MK2 Spool Holder uprights are a nice design and pretty strong, the way they hold on to the spool is less than sufficient and really didn't fill me with any confidence that 1kg of filament wouldn't come crashing down onto my print bed, mid print. With this in mind I wanted to keep the original uprights but utilise them in a better way to give some security, and allow them to store two spools at once, as I like to keep a "Draft" filament, and a "Production" filament toge