Theres plenty of ideas around here. Use the search. Theres also a tutorial in apprentice tokers by sems which is great.
I recently made a small pipe just out of brass fittings from Home Depot. No carb of course, but it's a great little pipe that hits very nicely.
i recently made one out of a bunch of bottles taped together and a soap dispenser as an ashcatcher its really fun to do cause you can get creative if you do make one i'd pick up a hot glue gun and a bunch of sticks it makes em alot better