Introduction: French Press in a Nalgene

Ah, Coffee. For many of us it's an essential part of our morning routines, whether it's the warm mug at home or the to-go cup on the way in to work, straight black or with cream and sugar, decaf or with an extra shot of espresso (or two?)- and it's no exception when we're away enjoying the great outdoors. There are all sorts of options for making coffee on the trail, from products like the beloved AeroPress to using old socks as makeshift coffee filters (um, gross). Or, you can follow this instructable to turn your Nalgene water bottle into a compact, lightweight, coffee brewing machine!

As is often the case with great ideas, I discovered that I was not in fact the first to come up with this concept. Here's a kickstarter from 2014 for a product called the "Press-Bot" :

This DIY version has a similar design but is constructed using recycled parts, miscellaneous hardware, and basic hand tools- oh, and may cost you less than a bag of coffee beans. So finish that cup in front of you and get to work making your very own French Press in a Nalgene!


For this project you'll need:

  • Nalgene wide-mouth water bottle (1)
  • Nalgene wide-mouth water bottle cap (1)
  • French Press (1)
  • 1 1/2" narrow brass hinges (2)
  • 3/4" stainless steel filter screen (1)
  • M5 x .80 lock nut (1)
  • M5 x .80 wing nut (1)
  • M5 x .80 fender washers (2)
  • 1/8" Aluminum pop-rivets (short) and washers

And the tools you'll need are:

  • hacksaw
  • drill and drill bits (at least 1/8", 3/16", and 1/2" bits)
  • rivet tool
  • M5 x .80 die and die wrench
  • vice grips
  • metal file, sandpaper
  • sharpie, straightedge
  • c-clamp

Make sure that the French Press you plan on modifying has a plunger that will fit inside the body of the Nalgene . You'll have some play with the filter screen and the spring around the edge, but the solid piece in the middle (with the holes in it) needs to be the right size. I was unable to find the exact brand/model of the one I used, but it looks like most are a standard size and that even something like this would work:

The plunger rod from my press had M5 x .80 threads where it screwed into the base. Again, this is likely going to be a standard size, but if not you'll need to get different fasteners. You can always bring your parts into the hardware store and size things up there.

Step 1: Disassembly

Remove the cap and plunger assembly from the press and unscrew the plunger rod from the base to separate the components. We will be saving the plunger rod, spiral plate, and filter screen for this project. The other pieces can be tossed or saved for another use. Now your're ready to start hacking away!

Step 2: Cutting the Hinges...

Lay the hinges side by side in the middle of the spiral plate. The idea is to have the plunger base hinge in 3 sections- a middle section and the two sides. To create room for the plunger rod to fit through the hole in the center of the spiral plate, we will be notching out the middle inside sections of both hinges.

Use a sharpie to mark two horizontal lines just inside of the screw holes on both hinges. Make sure the to mark the side of each hinge with the three connection points to the hinge pin (see images). Cut along these lines using the hacksaw, and pull the hinge apart to make working with the pieces easier.

Round the inside corners of the cutout area to create more clearance for the middle hole. Use a c-clamp to hold the pieces and round them off on a metal file laid flat on the table (or something like a bench grinder would work fine as well). Clean up any rough edges using sandpaper (I used 230 grit). The hinge can now be reassembled and set on the spiral plate to check the fit.

Repeat the above steps for second hinge. Once they're both done, check they're combined fit on the spiral plate. They should sit flat and squared up with one another, leaving plenty of clearance around the middle hole.

Step 3: ...and the Spiral Plate

Find the ends of the spring that coils around the edge of the spiral plate. Take one of the ends and begin twisting it out, and contintue until the entire spring is removed. You can set this aside for the time being.

Flip the plate over and lay the hinges the same way they were, just on the bottom of the plate this time (this just makes marking and cutting easier). Try and position the holes of the hinges so that none of them lie over pre-existing holes in the plate. Take a sharpie and mark where the top and bottom of the hing pins sit on the plate. Then, use a straight edge to connect each pair of points so that you have a two vertical lines running the lengh of the plate.

Secure the side of the plate not being cut to your worksurface using a c-clamp (or a bench vice would work even better). Cut along your marked line using the hacksaw, being careful to not bend the metal (especially towards the end of the cut). Flip the piece around and cut the other side to leave you with three sections, the middle and the two sides.

Smooth out the cut edges of each piece using the metal file and sandpaper. Lastly, file down the cut edges of the rim where the sections hinge to give them a slight angle (see images). This will let the pieces fold together without binding. Now we're ready to start putting things together!

Step 4: Riveting the Plunger Base

Put the three sections of the spiral plate together with the rim facing up, and set the hinges on top. Make sure that the hinge pins are centered over the cuts between sections. Using a sharpie, mark the four holes of each hinge on the plate sections. Drill through at the marked locations using the 1/8" drill bit and clean up any rough edges with the file/sandpaper.

We're only going to attach the filter screen to the middle section because it doesn't have the ability to stretch with the upwards hinging motion of the assembly. I found that this works well enough, especially because the screen gets pushed against the plate anyways when you use the press (but if anyone has any thoughts on this I'd love to hear your ideas!). So, place all three spiral plate sections on the filter screen to properly center the middle section, but only mark the four middle holes. These can then be poked through on the filter screen using the same 1/8" bit.

Stack the pieces as shown in the images with the filter screen on bottom, followed by the spiral plate sections, and the hinges on top. Rivet through all three layers of the middle section, using a washer on the bottom of each rivet (the filter screen side). Repeat this same process for the side sections, only leave the filter screen free (only rivet the hinges and side plate sections together). Use washers for these as well. Lastly, coil the spring back through the rim of the spiral plate. This spring serves to not only seal the edges of the plunger base around the inside of the water bottle, but keeps the assembly popped open in the flat position (even when using the press, suprisingly).

Step 5: Modifying the Plunger Rod and Cap

The threaded section of the plunger rod needs to be extended to give the filter assembly more room to pivot once the nuts and washers are threaded on. Grip the plunger rod with a vice grips and use the die tool with an M5 x .80 die to roughly double the length of the threads (I found that ~ 2" of threads was sufficient). Work the die tool up and down the length of the threads at least once more after the initial cut to make sure that the threads are clean.

Thread the wing nut onto plunger rod with the tabs of the nut facing the handle, followed by one of the fender washers, the plunger base assembly, the second fender washer, and the nylon lock nut on the bottom. Check the operation of the assembly by folding the filter and angle it down the neck of the water bottle (if it doesn't quite fit you may need to drill out the central hole of the filter assembly to slightly larger diameter). Tighten the wing nut down onto the plunger base to make sure it stays flat when the plunger rod is held vertical. Reverse these steps to remove the plunger assembly.

Grab the cap that you plan on modifying for the French Press unit. First, you're going to want to drill out the middle of the cap using the 3/16" drill bit to give the plunger rod a place fit through. Dissasemble the plunger assembly and check that the plunger rod slides through nicely. Next, take the filter screen and position it near the edge of the cap to determine where the spout of the press will be. I used a 1/2" drill bit with the 3/4" filter screen to give myself extra material around the edge of the hole to secure it in place. Make sure when you're picking your hole location that you won't be drilling through the edge of the cap. Clean up the edges using a utility/xacto knife. Place the screen on the underside of the cap so that it completely covers the hole, and use the 1/8" drill bit to create holes for rivets to secure the filter screen. The exact location of these holes isn't especially important, nor is centering the screen perfectly over the spout hole (see images). Put the rivets in from the top of the cap and use washers over the filter screen side.

Reassemble the plunger assembly just as previous, only this time start by first putting the plunger rod through the cap. Stack the plunger base, nuts, and washers just like before. Use a wrench to tighten the bottom lock nut to at least a thread or two past the nylon. And that's it, you're ready to brew!

Step 6: Brew Some Coffee!

I hope you guys enjoyed my French Press in a Nalgene project, if you have any comments, questions, or suggestions I'd love to hear! This was a fun project for me to put together, but especially in contributing once again to a community that I was so fond of as a kid (I published my first 'ible in 2010, don't even ask how I still know my login info).

So keep makin' and keep caffinatin'


Coffee Speed Challenge

Third Prize in the
Coffee Speed Challenge