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.