Thumbtack Dart
Description
Just add thumbtack. These seem to work well with cardboard box based dartboards.
Instructions
This is a dual extrusion print. For weighting, I used 50% infill for b (the grip) and 10% infill for a, (the rest of the dart).
License
Thumbtack Dart by JavaGrinder is licensed under the Attribution - Share Alike - Creative Commons license.

Could you upload a printable .stl? Unless I'm missing something the top of the dart is floating above the other piece
It's a dual extrusion print, so b goes in that gap. I'll try to come up with a version that doesn't require 2 extruders.