This is a double yellow flag holder that allows auto racing course marshals to join the sticks of two yellow flags together making it easier to display a double stationary yellow flag during full-course caution race condition. It's based on a similar design that a fellow course Marshal had created. His design worked great but would easily slide off of the flag sticks, so I designed my own with side tabs that hold slight tension against the stick to keep it in place. I also added a knurled texture to improve grip.

This file include six different styles. No tension, light tension, and strong tension versions, in both smooth and knurled textures. The holes for the flags are 18mm in diameter, but you should be able to scale up or down in your slicer program to adjust for different stick diameters.

For strength, I recommend printing on the default 45 degree angle, as early on I had issues with the side tabs breaking along the layer lines if I printed them vertically.

I also do NOT recommend using PLA for any of the light or strong tension designs as it is not a strong enough material, and the side tabs can easily be broken. I had great success using PETG HF.