1. Knockbox
The first accessory on the list is the knock frame. This may not seem like a big deal, but if you've ever tried to get a puck out of a mobile filter and put it in the trash, you know it's a pretty big headache.
So I think knocking on the jamb is a must - not just a nice one.
2. Tamper
Next, we have tampering. Most espresso machines come with flimsy tampers that don't offer much in terms of tactile feedback.
Today, there are tens of thousands of models to choose from, so there's always something for every taste.
However, before ordering, you need to make sure it fits your basket/strainer.
Some tampers are precision tampers, which means they are only a few millimeters larger than the standard size—hence 58.4mm instead of 58.0mm.
The extra millimeters mean the edges of the pucks are also compressed and you don't have to worry about side channels.
3. Espresso scale
A scale is necessary if you want to take your shots seriously.
Of course, if you're going to use it to make a cappuccino, you can look at it by eye or use volume measurements, but I wouldn't recommend this method to budding baristas.
If you want to follow an exact 1:2 ratio, the only way is to use an espresso scale.
Of course, you can use any digital scale as long as it fits on the drip tray, but I recommend buying a scale made for coffee as it has a timer. Timers are great for dialing in and can help with consistency.
4. Milk pitcher (cappuccino accessory)
If you want to steam some milk, you need a pitcher. Sometimes they come with an espresso machine as an accessory, but usually you have to buy one separately.
It doesn't have to be a fancy branding or innovative design.
As long as you get the correct size and it has a spout for pouring latte art, you should be fine.
There are some latte art pots that don't have handles or have narrower tips, but whether that's your style is entirely up to personal preference.
One thing to keep in mind, though, is the size. You want a pitcher that fits your typical dose. It should be larger so that the milk has room to swirl in the swirl.