Nearly any DIY electronics project is going to 'look like a bomb'. I have made projects with my daughter and have advised her specifically to not bring it to school because of this exact concern.
Such projects usually consist of a micro controller (read small computer) specifically designed for wire connections to input /output components.
What are input /output components? Buttons, switches, and LEDs.
And then there's the wire. Lots and lots of wire associated with a DIY project.
Could a kid with that kind of knowledge build a timer to trigger a bomb? Yes. its not hard at all But the key is he doesn't have access to a compact explosive which is a highly controlled substance.
On the other hand, The kid is getting some awesome exposure which should help his educational objectives if he needs financial support.