The mini blinds in the garage when we moved into the house had a rod, but the part that hooks to the hook to open and close the blinds was gone. This cap solved that problem. The hole in the bottom of the cap is 11mm diameter. the rod comes in at 11.5mm. it worked out to be a nice tight fit.. although probably could have pushed the hole out to 11.5 so the rod will go all the way in. I was worried that the pla would snap, so it is bulky on purpose.

Since I assume there will be other diameter rods out there, I have included the fusion 360 export. you can import it back into fusion 360 and by selecting the right item on the timeline, can modify the hole size or the cylinder diameter.. etc.

ok did a little bit more tweaking- the original BlindRodCap.stl goes with the v6 fusion 360 file. The v8 version of the stl and fusion file has the big hole in the cap .5mm larger, the hole that attaches to the blind is chamfered, and I cleaned up the little bulge that stuck out on either side of the transition between the main cap and the part that attaches to the blind.

while I was at it I found that the distance between flats for the standard size hex wand was 5/16. From that I was able to use fusion 360 to modify the design to make a hex version.