I thought it could be interesting to watch different types of Parking-fee- and vending machines. They are more and more designed with big colourful buttons and graphic symbols easily recognizable. And with lots of smart functions.
I don't know if designing a software and let voters push a touch-screen is the best solution. It depends so much upon graphic design of the user interface.
3 generations of confusing automats
I have had recent experiences with very modern Parking-fee automats at Garages.
You slide your credit card through a machine on the way in, the gate opens and register the time you entered.
And when you are going to exit, you slide the credit card in another machine, and it calculates the fee, you punch your normal security-code, machine extracts exact fee from your bank account automatically, and opens the gate for you to drive out. (no big detailed instructions needed, almost everyone understand how it works)
There is also many options now to pay for parking with text-messages.
For vision- & sight-impaired you could let the machine read the instructions and use braille texts on the buttons. Just like ATM's.
Im just thinking that it would be possible to maybe have drive-through-voting, or letting people waiting in line prepare while they wait outside, to make the actual voting process faster inside the polling station.
Several analogies are possible to use ideas, details and graphic interface from such machines to apply on election process. I hope you will take a look at such machines, train-ticket-machines, PET-bottle-recycling-machines, phone booths and other userfriendly and "user-hostile" automatic appliances in your country and think about it. Come back here if you want to discuss.