...the problem with this, is that you can have a custom liner job done with your actual foot within probably the same amount of time that it would take to make a scan of the foot... For most custom liner jobs, such as with Zipfit or Intuition, it takes 10ish minutes and you're out the door in one trip and don't have to wait two weeks to see if your boot will fit or not. You also need to have the natural flexion of the foot, as well as how it sets into a custom footbed in order to really get the fit right. Even with injection foam liners, the whole process can be finished within a half-hour, and you can go skiing tomorrow.
Now, if you wanted to 3D print a thermoplastic custom boot shell based on a scan of the foot, then that could be something more interesting... I'm not sure how well the boots would hold up, as I'm unfamiliar with how well 3D printing has come along... but it would be far more unique, and niche, and you might just be able to find those customers out there who want that 'Ferrari' of a boot that almost nobody else has, or perhaps could benefit the full customization for a specific foot condition they have and are willing to throw the cash towards it.
Doing some research into how ski boot shells are made and how 3D printing might be able to accomplish what traditional thermoplastic processes can do with a lower initial overhead. Something to note is that it takes a LOT of money to create all the molds for all the new boot shells in every single size, and the companies need to do this every couple years when they modify their designs to remain competitive - this is why the old Raichle Flexon and Hardshell Snowboard boots have continually been built since the 80s, because the old molds have been passed around Montebelluna like the village bicycle. This is also why you don't see every boot come in very small or very large sizes - for example, some brands only have adult boots in sizes from 23-29. Some of them go down as low as 22 and up as high as 31 or 32, but very few actually make adult boots down to say, size 21 (thank you, Dalbello)
If you can use that to your advantage, it might help you out.. as you might be able to show that it could be a cost-benefit to a smaller operation not needing to have expensive thermoplastic molds built, and requiring large facilities for construction, and for people with unorthodox foot shapes, or other foot issues that occasionally cannot be adequately solved by mass-produced models (customers could include someone who's lost part of their foot to accident or warfare, or was born with a condition, etc).
That said, you're essentially entering prosthetics territory at that point, and you'll need to really do your research here, and get a bit 'engineery' - or at least understand it pretty well. Ski boots are technical as fuck - far more than they're given credit for being.
I really don't want to burst your bubble here with the boot liner idea, as I'm sure you're working hard towards this stuff, but my experience with this industry is that there have been a lot of gimmicky things out there that fail like a joke episode of Shark Tank (like... an absurdly and comically large amount - if you've ever been to SIA or ISPO or other outdoor product trade shows you would understand), and understanding the market as it is should be a large component of your entrepreneurship course.
...maybe none of this matters and all your course really wants you to do is hold a survey and show the results/write about it, but I had some time to kill while on the train tonight, so figured I'd offer you an obnoxious fuckin essay.
