The Gossen DigiS\ix is small, easily carried in a shirt pocket and if you really want to, it has a tripod screw so you could attach a hot shoe adapter and mount it to the camera.
The Gossen DigiSix is a lovely small light capable meter, very light and minimal in the pocket. No complaints about it's accuracy or metering capability. There are a few things though.
Although it's small, it's pretty big mounted on a hot shoe, and sticks out a fair bit.
The meter button has no guard, and due to it's location, it's easily press by pressure in your pocket or bag. So much so, that the battery is often dead when you pull it out.
The display reads in EVs, which you must set on a ring with small text. You then get a full range of settings, but I prefer a direct reading display on a digital meter rather than an extra step to get a reading. I find the numbers on the scale small and difficult to read, but that is probably age related. By comparison, the Sekonic Twin Mate is similarly small but has larger easier to read text, and the analog meter dial setting is quicker then the DigiSix EV setting dial - which defeats one of the advantages of digital displays... (Note the Sekonic Twin Mate is a digitally controlled meter with an analog display)
I still use mine though, it's hard to beat it for small and light.