I'd check for some ready made cases to get some inspiration - and then decide whether it's worth building them as diy. The original design from Neve used for the consoles involves some plastic parts, which hold the channel in place, they are most likely unobtainable and certainly way too weak for anything that is meant to be moved. Even in the consoles they were a pita...
I have experienced 1083 racks, that used the plastic holders - they needed constant maintenace. I have several 1073 racks which use a way better construction, the guy replaced the tiny plastic holders with massive ones. This works quite well, apart from that the general work quality was very sloppy and I had to reassemble the cases several times already in order to make everything fitting and reliable. So still no recommendation here unfortunately.
If I would build something like that I'd check into http://www.frontpanelexpress.com/ for the US or http://www.schaeffer-ag.de for Europe. Having all the parts made from aluminium by a pro and only having to assemble it seems to be a way to get a very good quality done, but still wouldn't be cheap and needs a very serious amount of planning. I wonder if it's worth the effort for just 2 channels.
The general problem is, that the channels are really heavy. There is no easy way to 'just fix it somehow' if it's supposed to last.
Maybe someone has an idea where to look for inspiration? The 1083 racks were made by Shep, dunno if they are still in business. The other guys site is still under construction. I could take some pics of my cases, but haven't yet worked out, how to post pictures here (shame on me...).
Anyway, a solution would be cool to have, I still need to rack 2 2254s!
Michael