Designed for the Zero Friction tees, but the model can be altered or scaled for other tee diameters. 

Zero Friction Tees are 4.3 to 4.4 mm diameter on average. Checking some of my wood tees, they are around 4.8 mm. So scaling up the print by 9-10% (4.8/4.4)  should provide the best fit. 

I printed in PETG since I plan on leaving it in the bag which is sometimes subject to the deadly summer heat + car trunk combo. PLA should work fine though as long as you don't let it get too hot.