Fellow Prismo attachment for AeroPress

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Espresso is my favourite way to brew coffee, but I can’t carry my espresso machine around with me wherever I go and my work doesn’t have an espresso machine in my office tea room. So I use my AeroPress and my coffee plunger. But recently I got to wondering if the AeroPress could be used in any way that could make something that was closer to espresso. Here’s what I found out.

The Fellow Prismo pressure-actuated attachment for AeroPress

After searching for different ways I could use my AeroPress coffee maker, I stumbled upon an attachment called the Prismo, made by a company called Fellow Industries. Fellow Industries is a San Francisco based company started in 2015 by Jake Miller. They make various coffee related products, with the Prismo being just one of them. The Prismo was first introduced to the world in late 2017. Since then, it’s been gaining popularity with AeroPress users everywhere. Let’s take a closer look at it.

The Fellow Prismo, which helps to get crema from an AeroPress
Click this image to view this on Amazon.

What is the Fellow Prismo and how does it work?

The Fellow Prismo is a pressure-actuated attachment for the AeroPress that lets you make espresso-style coffee, without the need to use the inverted method. It’s basically a custom AeroPress cap with a “no drip seal” and “pressure actuated valve”, as well as a reusable metal filter.

You’ve probably noticed I’ve used this term “pressure-actuated valve” a couple of times now and could very well be wondering “So, what is a “pressure-actuated valve”? I’ll break it down. In the case of the Fellow Prismo, the valve is the small bit of rubber with a cross incision on it that sits in the center of the custom cap. Pressure-actuated means that it’s pressure that puts the valve into action and pushes it open.

Before pressing your brew, the valve is in the closed position, which stops the flow of your brew into your cup. Only once pressure is applied by pushing down the AeroPress plunger into the chamber does the valve immediately open and push the brew into your cup like a jet stream. This is what allows you to produce a brew with the AeroPress similar to the inverted method, without using the inverted method.

This is different from the standard AeroPress cap, which can and does begin to drip into your cup once you pour hot water into the chamber (unless you’re brewing with the inverted method).

What comes with the Fellow Prismo for AeroPress?

Fellow Prismo cap

The custom cap has a pressure-actuated valve. It simply screws onto the bottom of the AeroPress chamber instead of the original cap, with the reusable metal filter placed in the cap. The pressure actuated valve stays sealed until you press down, allowing you to hold your brew in the AeroPress chamber. Combined with a “no drip seal”, you can brew a full immersion without inverting your AeroPress.
Close up of the underside of the Fellow Prismo cap, showing the pressure-actuated valve
Close up of the inside of the Fellow Prismo cap

Reusable metal filter

Compared to some of the metal filters that you can find for the AeroPress, this one is decent quality. Although, it does have a bit of flex, so you’d want to be gentle with it. It has a silicon cover around the edge of the filter which is not removable. I have noticed that it can get a little bit difficult to clean around the edges of the cover.

Close up of the Fellow Prismo 150 micron etched fine metal filter.

Each hole in the filter is… how many microns?

How many microns?

For starters, what’s a micron, you ask? A micron, also known as a micrometer, is a unit of length that is one thousandth of a millimetre. I wasn’t sure of the exact specs of the filter, as I’d read multiple variations. This page says the filter is an “80 micron” etched metal filter. Whereas this page says the filter is “150 micron”. And this page says the filter is “70 micron”. So which is it? Well, I decided to go straight to the source and contacted Fellow Industries to find out. Here’s my email.

My email to Fellow Industries that states "Hi, I'm an AeroPress user and I recently purchased the Prismo. I'm very happy with my purchase, though I'm still getting the hang of it and experimenting a bit. I was wondering if you could clarify something for me. On the product page of your website, it states that the filter is "150 microns" - https://fellowproducts.com/products/prismo/ - whereas on one of your earlier blog posts, it states that the filter is "80 microns" - https://fellowproducts.com/blogs/brew-guides/prismo-superpowers-for-your-aeropress%C2%AE - and then on Amazon.com it states that the filter is "70 microns" - https://www.amazon.com/Fellow-Pressure-Actuated-Attachment-AeroPress-Espresso-Style/dp/B079YBT2LJ/. I realise that the filter has probably changed over time. Can you please confirm which filter you are currently distributing? Kind regards, Marty"


And here’s their super-prompt response, received in less than 24 hours!

An email reply from Fellow Industries that states "Thanks for reaching out, Marty! We need to update those pages as the Prismo filter is 150 microns now (this change was made a few years ago). Let me know if I can clarify anything or answer other questions you may have! Best, Nick"

So there you have it. Thanks to Nick from Fellow Industries, we now know that the current filter for the Fellow Prismo is 150 microns. So that means that each little hole in the metal filter is 0.15 of a millimetre. That is tiny!

I was also really pleased with Nick’s prompt response. When a company takes the time to respond quickly to their customers’ queries, it tells me that they understand that their customers are important. That’s an A+ right there.

See the price on Amazon

Fellow Prismo instructions

It’s very easy to begin using the Fellow Prismo. Standard instructions are:

  1. place the reusable metal filter inside the cap, with the Fellow text on the filter face-up,
  2. screw the cap onto the AeroPress chamber, making sure that the Fellow logo icon on the cap is aligned with the numbers on the AeroPress chamber,
  3. measure 20g of ultra-fine ground coffee and pour into the AeroPress chamber,
  4. place the AeroPress onto your coffee cup or glass,
  5. slowly pour 50ml of boiling water (100˚C/212˚F) into the AeroPress chamber,
  6. stir the coffee vigorously for 20 seconds,
  7. let the coffee sit for one minute,
  8. place the AeroPress plunger into the chamber and give an initial quick, hard press to compress the coffee grounds, then maintain constant pressure until the plunger reaches the bottom,
  9. remove the Prismo from the AeroPress and wash all parts,
  10. drink and enjoy your espresso-style coffee.

This is the standard Fellow Prismo instructions and should produce a crema. If you’re interested, you can also use the Prismo to make cold brew.

Cleaning the Fellow Prismo

It’s recommended to clean the Fellow Prismo after every use to avoid it getting clogged up by coffee oils and negatively impacting your brew. Don’t use anything abrasive or rough though, only a soft sponge. It’s also safe to put it in the top rack of your dishwasher.

Another option is to simply clean it with warm soapy water. To clean it this way, all you need to do is:

  1. take everything apart and rinse it after use,
  2. attach the Prismo with filter back onto the AeroPress chamber,
  3. add some warm soapy water into the AeroPress chamber,
  4. press and pull the soapy water through the Prismo, and
  5. rinse any soapy residue off the parts.

If you wanted to, you could fill the AeroPress chamber with plain warm water and press it through the Prismo once more. This also would help to remove any soapy residue from all the parts.

Can you use the Fellow Prismo with a paper filter?

Sure. You can use a paper filter with the Prismo, but I don’t know why you’d really want to. After all, it’s designed to be used with a metal filter. The people at Fellow Industries surely spent months doing research and trying different options for brewing with the Prismo. Their decision was to design, create and package their own fine metal filter. I highly doubt they decided to pack the Prismo with their own metal filter just on a whim.

However, there is one method of using both a paper filter and the metal filter that I have tried. It involves tamping the coffee inside the AeroPress and then packing a paper filter on top of the tamped coffee grounds. In fact, in my somewhat short experience with using the Fellow Prismo, this has been the only method that I’ve been able to use to get anything close to a crema. I explain this method in more detail here.

See the price on Amazon


Overall I’ve been very happy with the Fellow Prismo. It makes a great brew and I definitely like the fact that I don’t need to use the inverted method to brew a full immersion coffee.

One thing I feel I need to comment on though is the price, as it’s pretty much the same price as the AeroPress itself. In the scheme of things, it’s not expensive, but it did make me wonder if I really needed it.

It’s delivered on everything so far, except I still struggle to get a crema by following the standard instructions. It’s fairly early days for me though, so plenty of time to refine my skills. It’s a quality product that I have no problem recommending. Click here to view it on Amazon now.

Have you purchased the Fellow Prismo or perhaps have a question about it? Perhaps you’ve had experience with a different AeroPress attachment? Let me know in the comments below.

Stay caffeinated!