Not sure if there are plans or where to get them, but it's easy enough to figure out a design that meets your needs.
The MFT/3 height with the legs folded is 180mm and is 1157x773mm. Do you need casters? Do they need to be locking? IIRC, the WoodRiver 2.5" Double-Locking Casters are 88mm in height. At what height do you want the surface of the MFT? Standard MFT height is 900mm. 36 inches is 920mm. Subtract 268mm from whatever height you want and that's the height of the panels for your base cabinet.
From there, it depends how you're going to mount the systainers. If you plan on 3D printing SYS-PRO v2 Sliding Rails, the width is 412mm, Festool SYS-Rail is 418mm, and SYS-AZ Drawers with specification is 427mm with a minimum depth of 380mm. Your base could be 800mm deep to accommodate Systainers on both sides and it won't change the overall feel. My friend did exactly this with his MFT Base. You could even buy your own drawer slides and make sliding platforms to access your Systainers (I think this approach a lot - and use 14" slides with 427mm width).
The best thing about developing your own plan is that you design it to meet you needs and desires.