One trick to making sesame tahini with an immersion blender (if you have one strong enough—I’ve tried this at friend’s houses and their blenders were too weak) is to put a few dabs of water on.
The less water the better; water counter intuitively makes the seeds harder to blend (they just float apart) but makes the seeds less likely to fly away out of the blending jar. Juuuust enough so they rest heavily in the jar. I don’t measure it out, I just sprinkle a few drops.
I know it’s a culinary crime against taste & tradition to use unhulled seeds but I do, if I’m cooking for only myself, since they have more minerals.