The ONLY way I can see this working is if your parts can ALL be 3-D printed in their entirety or milled in under an hour. That then relies on a very very good printer set-up, likely one that you own and have used for at least a year (temp/humidity issues). You can do some electronics and PCB design with a mill and a copper plated proto-board (mill away copper plate and you can make crude PCB 'wires'), but you still need a fully functioning and stocked components chest or you have to wait a week for Digikey. If the zeitgeist is going towards IoT stuff, and I think it is, then you must wait for electronics parts to link the 3-D printed gizmo to the hackers waiting to make it a spam bot. 3 months is unlikely to be enough time to really get anything working without a well stocked lab.