Not too many drop spindles on Thingiverse, so I figured I'd add one of mine. I used Tinkercad to design it. Used Online-Convert.com to convert the Celtic knot from a .jpg to .svg. The spindle fits snugly into the whorl, but I secure it with a little hot glue just to be sure it doesn't fall apart.

I printed this on a balanced setting with 50% infill. You can make it a heavier whorl by increasing the infill density. I used a 7mm raft on both, which I found was necessary to keep the spindle nice and straight.