I'm working on a prototype for a project and I need to source a circular LCD countdown display timer - see attached rough sketch.
The clock (timer) must only countdown days automatically, not hours, minutes or seconds, and be operated by a battery that you would normally see in a digital wrist watch or car key fob. It needs to be simple and basic in functionality. If I want to set the timer to countdown from 10 days then I push the + button until I get to 10 and if I leave it for 3 seconds it will set on this number. It only requires 3 digits so the max number of days is 999. Ideally, when the timer reaches 3 days the display changes color to yellow and when it reaches 0 days, red.
Size - it should be 1.5 inches diameter, 2 inches max, and as thin as possible.
It will need a thin plastic or rubber transparent cover to protect it from water but at the same time this should not impact its visibility or functionality of the +/- buttons. If this was not possible then I'm sure I could have this done at my end.