In this guide I’ll show you how to make a DIY cold drip coffee maker for $40.

If you’ve ever tasted cold-brew coffee, you know that it’s damn good. It is much smoother than hot-brewed coffee and has a sweeter and more complex flavor too.

The reason it tastes so smooth is because it is less acidic and bitter than normal coffee. The cold-brew process doesn’t extract as much of the compounds that produce these flavors in hot-brewed coffee.

Less acidity means it is easier on the stomach, too. Many coffee experts claim that cold-brew coffee is about half as acidic as hot brewed. And even if you don’t like cold coffee, you can always heat it up in the microwave before drinking. Beware though, the jury is still out on whether warming up cold-brew alters the taste.

The biggest downside to cold-brew coffee is the time it takes to make it, which can extend over a day if you are doing a large batch. But, if you enjoy the process, it makes the time go a lot quicker. But enough about cold brew, on to the build!

Step 1: The Parts

Below I show where I got the parts for my cold brew tower and their approximate costs. These places are just a recommendation where to find them. You can definitely find a lot of these parts at most hardware stores, and I’m sure you could even find everything online if you wanted to. As far as the costs, you will probably have to buy some of these items in bulk (like the copper) so you may spend more than $40 to make one but it shouldn’t be too much more.

Tower

3, 2 foot pieces ⅝” o.d. coiled copper tubing (Home Depot) - $8
3, 3.75” pieces of ¼” o.d. refrigeration coiled copper tubing (Home Depot) - $0.50
3, #0 11/16” (wide end) rubber stoppers for feet (Ace Hardware) - $1.20
4” equilateral triangle of 24 ga copper sheeting (Amazon) - $0.75
3, ½” copper end caps (Home Depot) - $1.35

Water Bowl and Coffee Grounds Glass

1, ~1L glass spherical fish bowl (Wal-Mart) - $2
1, 1/8" x 1.5” brass pipe nipple (Ace Hardware) - $3
1, 1/8” MIP x 1/8” FIP Needle valve (Ace Hardware) - $7
1, 3/8” x ¾” steel sleeve (Ace Hardware) - $0.70
1, 5” tall by 3” wide glass or glass jar (World Market) - $2
1 paper coffee filter (Wal-Mart) - $0.05
1 piece of felt cut into a 2.25" circle (Michaels Arts and Crafts) $0.05
4, 3/8” rubber washers that fit tightly around nipple (Ace Hardware) - $1.20
2, 7/8” wide stainless steel washer (Ace Hardware) - $0.30
1, 1.5” long, 1/8” NPT lamp nipple (Ace Hardware) - $2
3, 1/8” NPT round lamp nuts (Ace Hardware) - $2
1, ~¼”(narrow end) cork (Ace Hardware) - $0.50

Coffee Pitcher

~1L glass carafe and lid (World Market) - $6

TOTAL - $38.60

Step 2: The Tools

Here are the tools you'll need to build your cold drip tower:

Hacksaw
Torch
Copper soldering materials (solder, flux, brush, emery cloth)
Drill
¼” drill bit, 1” hole saw bit, 3/8” diamond hole saw bit
Hammer
Masking tape
Tape Measure
Curved surface to bend pipe over (I use a 1/2" conduit bender handle)
Bailing wire (or steel wire) to hold tower together while soldering
Teflon tape
Clear silicone
Adhesive
80 grit sandpaper (optional)

Step 3: Cutting and Bending the Pipe

Cut 3, 2 foot lengths of copper pipe and straighten as best as possible (use a mallet and a flat surface)
Sand all pipes with 80 grit sandpaper for polished look (optional). It is quickest to use a belt sander if you have one
Mark a line at 11” and 17.5” from one end of each pipe. We will call the end that you measured from the “bottom” of the pipe
Using a rounded surface, bend copper pipes about 4” of deflection on the bottom end of the pipe and 1.5” of deflection on the top end. Bend the pipes a little bit at a time at different points along the pipe. If you bend the pipes over just one spot it may result in a kink. The bending should result in a shallow C shape like shown above
Cut a 5/16” wide slit at each 11” marked line with a hacksaw. Make sure slits are centered on convex side of pipes

Step 4: Constructing the Tower

Cut 4.125” equilateral triangle out of copper sheet and file edges
Hammer dents into triangle in a repeatable pattern. This will add strength to the copper and add a nice texture
Drill a 1” hole in center of the triangle for the coffee grounds glass bottom to sit in
Cut three 3.75” supports out of 1/4” tubing. Sand (optional)
Drill 2, ¼” holes in each pipe at the 17.5” line. The holes should be about ¼” from the center of the convex side of the pipes
Quickly rough up the following areas with emery cloth to prep for soldering:
1. Each corner (top and bottom) of triangle shelf
2. Around each slit in each leg ½” from the ends of each support
3. Where supports meet legs
Wipe each sanded area clean and make sure not to touch.

Step 5: Soldering the Tower

Brush a layer of flux on each sanded part
Lay two legs on a piece of a 2×4. Bottom of legs should touch the work surface
Insert copper shelf into two legs
Insert one support between two legs
Wire tie two legs to hold together
Make sure everything is aligned
Solder shelf and support
Place shelf into third leg and insert remaining two supports
Wire tie all three legs tight together. Stand the tower up.
Check alignment and solder remaining joints. Not going to lie, it’s tough to get everything aligned just right. Have someone hold it in place (with thick gloves) if you need to while soldering
Wipe clean excess flux and let cool
Polish dark and dirty spots and excess solder with sandpaper
Place a dab of adhesive on the three rubber stoppers and insert into bottom of each leg. Twist slightly.
Place a dab of adhesive on the inside of the three copper caps and insert onto top of each leg. Twist slightly.

Step 6: Drilling the Glass and Attaching the Valve

Drill 3/8” hole in center of bottom of coffee grounds jar and center of water jar with diamond hole saw bit. Use masking tape to start holes so bit doesn’t wander. Keep the bit at an angle at first and slowly move it towards the perpendicular. Use the low speed setting on the drill. Remember to keep jars under water while drilling and don’t put too much pressure on drill. Think of it as “carving” out the glass. For the thicker-bottomed coffee grounds glass, it takes about 10 minutes of straight drilling. If you are using a plug-in drill, BE VERY CAREFUL NOT TO DROP THE DRILL IN THE SINK. Doing so could electrocute and potentially kill you. It’s best to use a battery powered drill here.
Lightly sand sharp edges
Apply one wrap of Teflon tape to one side of 1.5″ pipe nipple making sure to wrap clockwise. Insert pipe nipple into female end of valve and tighten.
Place rubber washer, metal washer, and steel sleeve on one end of nipple
Place thin layer of silicone on one side of this rubber washer
Insert nipple into bottom of water jar
Place layer of silicone on other rubber washer
Insert other rubber washer and round nut on the bottom inside of the water jar over the pipe nipple. Tighten LIGHTLY. Test for leaks. Tighten a little more if it leaks and test again.
Place thin layer of silicone on one side of remaining two rubber washers
Place one rubber washer on one end of lamp nipple
Place one round lamp nut about 1/2″ from one end of lamp nipple
Insert nipple through bottom of coffee grounds jar from inside of jar
Place other rubber washer and round nut on the bottom of coffee grounds jar over the pipe nipple. Tighten LIGHTLY. Test for leaks. Tighten a little more if it leaks and test again.

Step 7: Make Some Cold Brew!

Here’s a basic recipe and instructions to break in your DIY cold brew coffee maker. Remember, it is more art than science to make a good cup of cold-brew. Feel free to experiment with different coffee beans, drip rates, grind of coffee beans, and volumes of coffee and water to produce a cold-brew you love! For more recipe ideas, check out this compilation of cold-brew recipes.

You will need:

Scissors
Scale (optional)
1 paper coffee filter
100 grams (~1 heaping cup) medium ground coffee beans
600 grams (2.5 cups) unchlorinated water
400 grams (~3 cups) ice cubes

Place coffee pitcher under stand and water bowl on top of stand. Make sure valve is closed (all the way clockwise) on water bowl
Pour ice and water into water bowl on stand
Place felt filter into bottom of coffee grounds glass. Pour in coffee grounds and place on stand. Pipe nipple on bottom of glass should go through hole in stand
Place cork in pipe nipple under coffee grounds glass
Cut out a circle about the size of the inside diameter of the coffee grounds glass from a paper coffee filter. Don’t worry about cutting perfectly. This filter will diffuse the dripping water evenly among the coffee grounds. Set filter aside
Open valve to a steady stream until coffee grounds are fully saturated and you don’t see any dry spots around the sides. Place paper filter on top of grounds
Wait one minute and then remove cork
Adjust valve to drip to about 40 drops a minutes. Check every hour or so and adjust valve to maintain drip rate
Allow 4-5 hours to brew, until water stops dripping. Enjoy immediately or refrigerate