hi tvtech,
I ran my own electronics design and manufacturing company for many years, my best advice to you is to avoid customised cases/boxes at all costs, [pardon the pun]
Find an off the shelf case/enclosure that is as close as possible to the 'ideal', then modify your design to suit, also ensure the cases can be sourced from a number of suppliers. There are lots of ABS/plastic case types available, also dont forget the anti tamper screws.
When you find the case that will do the job, produce the machining drawings and contact your local machine shops for quotes to do the required machining and engraving.
Initially go for small quantities, say 6 or 10 cases.
Regarding the school recharge, I would suggest a dedicated charger at the school/s that could charge say 10 pupils light units. This will be cheaper than a inbuilt charger and the light unit could be smaller.
If you ever get to production quantities, say over 500 light units, then look around for a model shop/moulding shop to produce the cases.
Regards