I want to know what you use.
I often take model:cycles or MC-101 with me for an hour or so in a cafe … but not sure I’d take anything bigger or more noticeable … e.g. even though they’re portable devices, I think I’d feel self-conscious about all the lights on a deluge or polyend play.
You ?
I feel self conscious holding any luxury item worth the cost of a phone or more in public, even if it is a tool for creation. I just don’t like drawing attention to myself in general however, so I’m probably odd man out. I’m sure the correct answer here is a laptop computer and headphones so people think you’re working.
Polyend Tracker is my go to for cafes, flights, or any travel really.
A book.
I never go to a Café but when I bring something to work, it’s the Syntakt.
How about a volca and 1 behringer pedal? that might be in my comfort zone / price range.
edit: noise cancelling headphones will fix that loud monitoring problem but also set you back an unfortunate penny.
I’ve taken the Microfreak out a few times. Also my Volca FM. It’s fun to just be limited to the one device and your imagination. I have gotten exactly one comment about it, which was approving. (Most people don’t really care what you’re doing as much as you might think they do.) The main drawback is that I have to monitor louder than I usually do, which can get tiring.
I don’t have one but the Dirtywave M8 has to be the winner for this kinda thing, surely?
Definitely ime. Anyone who’s looked over thought I was playing gameboy or had a weird phone
Or maybe one or two Nanobox from 1010music.
Powerbank would be annoying tho and still looks too curious for people to leave you alone
I always thought a Line6 Pocket Pod might work well for mobile effects since it has a headphone output and isn’t super expensive, but I haven’t actually tried one. Actually, NTS-1 might be a good choice to keep it Korg.
What about bringing a 25 feet extension with a power bar? Would that bring attention? 
Battery powered OP-Z but with lights and projector
dot matrix gameboy with an lsdj cart for the win
ATM I take the Nanobox Razzmatazz everywhere with me. I got a power bank approximately the same size (actually tinier) and just hold them both in my hand. It’s really not much trouble.
The Razzmatazz has enough depth to keep me absorbed for many many hours. I totally loose track of time 
Used to take my OG SP-404 on long coach rides. Pre-USB powerbank days so loaded with batteries. Got into some interesting conversations. Met a homeless guy who used to DJ.
But for a café, a laptop with headphones or a book will do just nicely.
I would probably get robbed if I took any gear to a café.
I’m also too overly self conscious to do anything like that. I’d be worried about a fellow gear nerd stepping up and being like “hey! It that a… ?”, where I would have to respond with “Step away…NOW” 
Or “hey, you know there’s a shortcut for that…” 