Actually what works great is a Swimming Pool Noodle. It has a hole up the middle of it and you can slide it on PVC pipe or steel Pipe. We make our own T's , everything comes from a Hardware store, but the Noodle. Plus they are portable. Plywood, Steel pipe and the threaded in you screw to the plywood, so you can screw the pipe to the Plywood. Then you slide on the Noodle, leaving nothing but Noodle on the Top to put the ball on. Noodle is cheap and easy to slide on and off and you can adjust the height.
I was thinking about putting pipe insulation over the PVC and it should be fine. Maybe I will duct tape a noodle over it cuz its thicker. But its alot cheaper than the original tee, they are $99 bucks.
With the tee forward design, you can't drop your hands and have an uppercut swing or the bat will never hit the ball, and with the L shaped arm it keeps you from casting when you swing or again you will hit the L shaped arm.. So it helps train a hitter to keep the bat in the zone with a level swing and compact swing.
At contact I see the bat head on it's way back up. When you say "level" my question is always level to what? I don't really think about a compact swing. I think about a quick swing and the compact flows from there. I understand you are trying to avoid this Photo 24 of 31, Analysis but the wrists should be uncocking and the bat whipping about the time it gets to the vertical part of your tee. Could this swing be accomplished on your tee? Photo 9 of 16, Fastpitch