Sounds like another very good use!
Distance between centres of the HDMI connectors is 25mm. This is what I used for the original Simple Pi Rack, when I was mounting on the audio and video jacks:
http://www.raspberrypi.org/phpBB3/viewt ... 40&t=34987
back then I used the HDMI connector for pulling the Pi out of the jacks. What I didn't think about, when turning the Pi round, was that the audio and video jacks are so much thicker and that sticking with 25mm would mean so much less room to get your fingers in to pull them out. Adding an extra 5mm should help, but them the whole assembly might not fit in the shoe box.
Speaking of which, I've been experimenting with stripping the outer coating and unused twisted pairs from the very short Cat5 cables. Reasons for this are that they are very inflexible, and take up more room than they should, and that the protective coating is unrequired in my environment. And, I reckon the original standards were designed for much longer cables, and will have practically no bearing on Fast Ethernet over a distance of 20cm. Also doing the same for the USB power cables, for much the same reasons (though did leave the unused data lines in, otherwise they were too flimbsy.) Compare the difference:
The assembly is much narrower now, though the nakedness of the cables takes a little getting use to:
And, of course, it all fits in the shoe-box much neater:
I'll update if any problems result!