I had an old D-Link DUB-H7 USB 2.0 hub laying around. It has 7 
ports, plus a host port on the back, and a 5v 3A power supply.
It's "smart" in the sense that it doesn't power up unless it 
detects a host (5v and sensing on D+/D-). That means it won't
power up the Pi, you have to power the Pi from another source,
and use this just as a hub. But, it comes in a handy little 
plastic case with lots of interior room, and it comes apart 
and goes back together really easily, so I figured I'd give 
it a go and see what could be modified.

First issue to solve is the "smartness" of the darn thing. The
quick and easy solution is to connect the 5v line on the host
port to 5v on the board. There are several pads on the back
with constant 5v (they appear to be for poly fuses that are
not on the board) so I connected it up to one of those. I also
bridged one of the set of pads, so one of the ports is always
powered up.

Next, I wanted to put the Pi inside this thing. The easiest
way was to do what other USB hub modders have done, which is
to connect the Pi Zero's PP22 and PP23 pads to the D+ and D-
respectively, and connect 5v (again from one of the poly fuse
pads, or one of the ports) and ground up to PP6 respectively.
To be clear, that's PP1 to 5v, PP6 to ground, PP22 to USB D+, 
and PP23 to D-. That all worked, the hub and pi both power
up together when the power is plugged into the hub.

The Pi Zero fits easily inside the case. I drilled 5 holes
in the top of the case; 4 holes to mount the pi, and one
large vent to let some heat out. I went to Ace Hardware and
purchased 4 nylon screws and 8 nylon nuts. The Pi zero is
snug up against the top, but because of the way the top is
moulded, there is air space between the components on the Pi
Zero and the plastic. I have mine flush against the back,
so that the HDMI port is readily accessible (you have to
cut a slot for it.)

It's not the tinyest thing out there (there are several
USB hub mods out there that almost match the Pi Zero in
form factor!) but I had the thing laying around, so it was
free. It has plenty of power, and now I can use it as a
tiny self-containted computer with 7 USB ports. You could
easily make the SD card accessible from the outside if you
wanted.