Here is some food for thought:
A deck of modern playing cards is like a distant ancestor to the 3DS. Yes, I said "modern"; playing cards have existed for a good while in human history, but there was a lot of variation until relatively recently. So... while your single player options were somewhat limited, hey it was a game you could take with you that could fit in your pocket. They also weren't too pricey.
Standard playing cards aren't the only card games before TCGs; someone just figured out how to take a relatively inexpensive physical product and get people to pay a high markup for it. Yeah, think of Magic: The Gathering and card games as being not unlike Starbucks and coffee; even good quality cards are still just cardboard with glossy stock (and/or foil) around them, with stuff printed on them. Sure it costs money to design, maintain, and market the game (which includes organized play) but trust me, selling TCGs still has a lot of room for profit as the MSRP. In reality though, they ought to be an inexpensive, pretty portable game.
Don't give up on a "duel disk" like system but realize it isn't solving a practical problem that applies to most people. Carrying around your collection is difficult, but a single deck is only a little bulky for the average pants or jacket pocket. Split it into two or three smaller sections and even that wouldn't be an issue (though you'd then have some issue carrying your wallet, keys, and phone). If you have a briefcase, book bag, decently sized purse, or even sufficiently voluminous pockets (like cargo pants), you can probably carry a deck easily enough. Local coinage can handle being damage counters and a randomizer, even. The practical solution for playing most TCGs on the go already exists, but can be pricey; for Pokémon you play the PTCGO, Hearthstone is already an eTCG only game, and many other games also have official (and of course unofficial) programs so that your mobile device can play them. Bam! Walk, talk, and play all at the same time (though probably not very well).
When you are allowed to work on something that really is about creating a marketable product, see if your class can design something like a desktop version of the dual disk. Maybe it just has a playmat capable of scanning and recognizing card faces, and it plugs into a TV (instead of projecting holograms =P) to show the "action". You'd have to buy the programs for individual games as well, because I am not expecting a naturally universal device. For your actual project, consider trying to design a sturdy, lightweight, collapsible chair/desk combination. You know, the kind of chair/desk like you see in many classrooms. This helps various students, professionals, and gamers by giving them something that might collapse into a briefcase sized object but means they always have a place to sit and a surface upon which to play (or work).
Sorry if this sounds like a buzzkill. ^^'
