1. An electronic labeller.
Not cheap. But very, very necessary.
This model allows for different size tape and different font sizes.
It also has a wide range of characters, including mathematical symbols.

2. Trays
More specifically, gratnell trays.
Durable, stackable, availabe in a range of sizes and colours.

3. Sweet boxes
More specifically haribo boxes. For storing all the small bits; everything from protractors to spatulas to  test-tubes.
They also act as little basins of water if need be. And they’re all completely free.