The purpose of this design is to create a simple and very effective spool holder for the filament shelf Joel (3D printing Nerd) has installed in his workroom.  These were designed to minimize print time and material utalized.  There are two versions.  One is friction fit or superglue (depends on your printer's tolerances).  The other design uses m3 bolts or screws. The completed parts are designed to sit on top in place on the rails of Joel's impressive rack (the shelf can be seen in the contest video) https://www.youtube.com/watch?v=1cWoeDfasJc&

For this design to work you will need these not printed parts:

• 4 x  608 bearings (skate bearings)
  https://www.amazon.com/8x22x7-Shielded-Greased-Miniature-Bearings/dp/B00NX23HGQ/
  
  
• 4 x M3*12 screws (hex heads)
  https://www.amazon.com/uxcell-M3x12mm-Socket-Screws-100Pcs/dp/B0143GZIHQ/

The above parts can be purchased most anywhere online, keep in mind, local hardware stores in the USA typically don't keep things that small in stock.  You can usually buy the bearings at a skate shop or even a sports store that would sell roller blades.

For the kiss_minimal you need to print the part 8 times.  This will give you a set of 4.

If you want to go with the recommended m3 bolt version, print kiss_m3_inside 4 times and kiss_m3_outside 4 times.

Assembly:

If you printed the version that requires a bolt: Just hold one outside print and one inside print together with the bearing in the center of the two and secure it with your m3 screw.  Enter from the outside print (has a larger opening) and the bolt head will secure flush.

if you printed the minimal version you may get away with just assembling everything and friction is perfect.  If not, you may need to keep things together with a dap of superglue.  Just make sure the bearing is in place before superglue is involved!  Personally, i don't like to leave things to chance with moving parts.  I recommend using glue or the other version.

You will need to make 4 of these parts total for the complete assembly.  The nice thing is no matter the width of the spool this system will support it.  I am also a big fan of using bearings and keeping drag down to an absolute minimum.  Then you have just one less thing taking away from your print quality.  You can print several of these (for multiple printers, but I would recommend printing in a color that stands out because they are so minimal, you will want to make sure its easy to spot them on the shelf.  It may be hard to tell the difference between spools being stored and being printed with because they will be on right next to each other.

https://en.wikipedia.org/wiki/KISS_principle