Hi Laurin - maybe a student OT would be the best person to help with your project (I'm not sure where you are but this link will help you find your nearest Uni
http://www.cot.co.uk/become-ot training OT's). I'll also tweet your request and maybe someone will come forward via netbuddy!
Have you heard of a time timer
http://amzn.to/xC7aPa? They are brilliant (but expensive) and can often help people who can't properly understand a standard timer.