All pipe/hose connections have to be absolutely watertight and I recommend a test with the reservoir filled but the coffee maker not plugged in. Check for leaks after 30 minutes or longer.
The electrical connections should be at least as well insulatad as in the original "donor", when you solder the copper pipes use leadfree solder and when using epoxy glue follow the instructions carefully and work in a well ventilated area!
This said, let's have a look what we need.
Materials and tools which will make completion of this project a lot easier -_^ :
Donor = Coffeemaker from the Salvation Army
Wood to build the frame
Copper pipes and fittings
Water reservoir - I used a aluminum water bottle
A nice coffee/tea pot
Filter holder - in my case a pretty porcelain lamp shade
4 rubber feet
Ruler, tape measure, compass and caliper
Drill press + drill bits
For some time I wanted to make a steampunk coffee/tea maker but I couldn't think of a nice water reservoir till I saw this aluminum water bottle at the dollar store. As luck would have it, the opening had a 3/4" FPT (female pipe thread) which could be easily fitted with the male counterpart and further hooked up to the heater element. (You can see it on a picture later) The other problem was the wooden base but I was lucky there too.
If you want to see how a coffee maker works, check this really good video clip: http://vimeo.com/2193258
Of course you could argue an electrical powered coffee maker is not steampunk at all, but then I want to see the coal/gasoline driven coffee maker you've built ;p