Would the test finder need to be disabled along with the vending machine too or does it just not work?
And I would say the scissors/eraser being missable could work as it COULD be similar to throwing an Oreo (it too can technically be risk/reward since you could miss throwing it at Circle). But I think it working like "an apple for Baldi" could work really well.
For the green chemical, my original idea for it was to create a temporary wall to block teachers, but I felt that would give problems for the AI that already seems to like getting stuck in places?? But then again you can stand in front of them and they eventually change paths too, so I'm unsure about it. I feel like the gamble could still work somehow if maybe toned down.. OR..
Going off that poster idea, I feel it would make sense if the poster itself was put in Miss Bloomie's spawning classroom. It doesn't have to explain OUTRIGHT, it could just look like a chemical recipe where it shows items being added like "speed + health + soda = strange chemical??". Something like that anyway. To make posters not feel out of place, you gotta make them IN place.. so the health and speed chemicals (I assume they are anyway) could have something about them in Miss Bloomie's room too. Miss Circle could probably have something in her room regarding Oreos too. Posters advertising the soda in the cafeteria, etc.
But anyway, credit me if you'd like, I don't mind much.