Yes, another i3 spool holder…But do you need to quick swap different spools with 1.75mm filaments? I like the simplicity of the original Prusai3 Plus/MK2 spool holders, but I refuse to move it along tight dural frame with every different spool width. If you have some old/spare 8mm rod (156mm or longer), my design is directly for you. Simply lift the axis and change the spool with filament. It is suitable for the original Prusa i3 Plus/MK2 with dural frame or clones. No bearings needed at all.
[UPDATE 2017-09-02] Added lighter Insert part "V3a" (less material, faster print) and Filament Guide (V3a) for full spools where filament tends to slide aside. All is printable without supports.
40% for both holders, 20% for the rest
You need to print one Insert (0.3 layers are OK here as it will have better grip with the spools and they will not slide from one side to other during 3D printing). Then two Holders – they are identical and you can play with more colours etc. Use more infill here (40% is OK). And the two Stoppers are there to minimise friction between the Insert and the Holders (and avoid the rod to slide to the sides). Use their smoother side on sides with the Holders. The Insert alone has sufficient friction to secure the rod between the Holders, but those Stoppers are simply an insurance. ;)
[Optional] Print also one Filament Guide part, it's simply attachable to main frame of original Prusa i3 MK2/Plus.