
Seven ports! I need to make a really short USB cable so that I can hook the chording glove up to it.

Four on the inside, three on the outside. USB-mini in the back, optional power supply.
The wristband is a padded velcro thingy that the company that a guy I know works for ordered by mistake. Normally, a smaller beige plastic holder for a barcode scanner velcros onto it; I took the velcro off the plastic thingy and put it on the hub.
My original plan was to get one of those four-port unpowered jobs, mount it in the original plastic housing, and also add slots for SD cards. I may still do that, since the guy has lots of these wristbands available. This approach means less work to do with a Dremel, but I like the idea of storage on the go. Perhaps one for each wrist, to support keyboard and mouse. (Hey, if I ever don't feel like chording but have the rig set up anyway, I can just plug an ordinary USB keyboard into my wrist!)
If I do make a custom wrist-mount, I might go all out and make a PCB for it using
this approach.
ETA: Three hours in, I'm still wearing it comfortably, which is impressive for me, since I usually fidget like crazy with bracelets, watches and things like that. I did flip it to the inside of my wrist, because I realised that the titanium bracers that Chris++ is making for the sleeves of my leather longcoat will go on the outside of my arms, leaving no room for an outward-facing hub, but I think it will fit okay on the inside. Worst-case scenario, the velcro straps are long enough that if I have to, I can wear the hub on my bicep. Time to get one of those retractable USB-A/USB-mini-B cables, the clicky kind.