Update 30 March 2018 - Added a STEP file to the download.
Update 23rd October 2017 - I've re-vamped this spool holder so there is now only one version that should fit all spools. The spool pole itself is now thicker (28mm) but the end ball has been replaced with a 'spool stop' which can be clipped on/off. This allows spools with a small hole to be used.
I designed this type of holder because I wanted to be able to quickly change spools safely. The stock ones are not very safe and the ones that allow you to balance the spool on top are also not ideal as there is a chance of knocking the spool off.
I have tested the strength of this holder with 35% infil and I had to put most of my body weight onto it before it broke, so 1KG filament spools are not a problem, however it does depend on the quality of your prints. Note this test was done on the older version which was 25mm thick, this new one is 28mm thick.
The filament guide clips into place and can be reversed when not needed. I have also added a split in the guide so the filament can be removed/placed inside the guide at any time during a print without having to break the filament. This guide is also reversible so it can be stored away without the guide part sticking out the front when its not needed.
The filament guide only needs to be used for problem spools that unravel or when you use sample filament that doesn't have a spool. When you are printing very tall objects this particular filament guide won't work that well, I will be designing a much wider one to solve this problem and it will clip onto this existing spool holder.
The 'loose spool keep' is for when you want to use some loose filament that is not on a reel. The keep stops it falling off the spool holder and works until the end of the filament is reached.