Why is that question mark hanging around in this handyman’s perfect dream?

In a wood shop I saw this neatly ordered board. Perfect? Almost! There was one screw were a tool was missing. I’ve turned it (sloppy...) into a white question mark. Why??? What??? Where???

[Wendy]

Just a little neater than Hubby's wall of tools, and cabinet of tools, etc...

[Diana]

So neat, compact and small.

[gloria jones]

Organization at its best...Great image

[Angelika van Rooyen]

Wow, so neat!

[Dianne]

Very tidy. I can see what’s missing - a spanner is hiding behind the screwdrivers on the bottom shelf. Quickly go and hang it up!!

[Etienne]

Cutting pliers or wire cutter ?

[Marloes]

@etienne I don’t know. Good guess, I guess ;)

[Helen Jane]

I feel there should be a spirit level somewhere

[Peter H]

Surely just for display, not work?