I have built a number of custom attachments to the lids of my systainers in the past. For instance see the thread: http://festoolownersgroup.com/festool-jigs-tool-enhancements/a-homemade-'office-top'-that-attaches-to-a-systainer-lid/
These attachments need to be somewhat changed in order to work with the new T-lock systainers.
Today, I made a template of a base that can be screwed to the lid. Other parts can then be attached to this base. I made the template out of 3mm thick Baltic birch. This material is certainly strong enough to serve as the base of all the attachments that I have in mind right now. So, I made three additional bases from the template and will be utilizing them soon.
For those who wish to make similar attachments, here is a photo with the various dimensions shown on it:
All the small notches are 8mm by 3mm.
Here is a photo of the template attached to the lid:
It attaches with #10 screws. I used screws that are 5/8 inch long. I am looking for some made of brass and with smaller heads but am not sure that I will have any success.
You might be interested in how I located the positions to drill the screw holes. I placed canoe tacks with filed down heads into each of the “receptacles” in the lid then pressed down my template to create indents in the correct spots:
I cut out a 384mm by 230mm rectangle on a table saw then made all the cut-outs with a jig saw:
I will post some more pictures when I have built some attachments.