Simple water level visualizer for hydronic systems. Attach a cork or some floating material to the circular plunger at the end (make sure it can fit inside the rest of the tubing). The tube is 8 inches long. If it doesn't slide well you can sandpaper down the plunger on the round sides just a bit and it will go smoother. I believe I've made adjustments so you shouldn't have to do that. Built in Fusion360.

Other notes:
- I made the seams random on the plunger because some prints would have issues with the screw mechanism. For the plunger screw end, just screw till tight. Otherwise it might break.