Maybe make a reservoir to hold lots of grounds and another for the water. Then put in a 12vdc camping coffee maker. Let the reservoirs dump the grounds in the appropriate place and the water. Let the coffee maker do it's thing. I guess it is a lot easier said than done. Just a thought. I am better a electronics than mechanical. Let gravity do it work with the grounds and water. Use a servo to open up and close the valve. Leave the hoses in place where they go. The tricky part is going to be put the coffee filter in right. If you have sanka, it will disolve in water so you could just mix the water and the sanka and not worry about a filter. hmm......