Below is a design for an MFT workbench assembly.  I have been watching all of the other designs posted here as well as Guido's and came up with this variation on the theme.  My objectives were:
1)  Clean up my pile of systainers and make them more accessible.
2)  Create an ability to use handtools (planes mostly with some hand sawing) with my MFT's.  By using Quick Clamps in the front extrusions of the MFTs and a sliding deadman (the tracks run full width top and bottom), there is lots of flexibility for holding pieces on edge.
3)  Create storage for lots of small parts and tools
4)  Create an easy way to cover the table with kraft paper for glue-ups, finishing, etc.

I already have two MFT 1080s and one MFT 800.  Not shown is a Chop Saw hood mounted to the rear of the middle MFT (helps keep sawdust from blowing onto a car in the winter).  The overall assembly is sandwiched between a tire storage rack on the left and a bandsaw on the right--the later should help stabilize the assembly further during handplaning.  The wheels aren't really necessary but may prove handy when it comes time to reconfigure things.

The beast holds up to four Systainer 1, five 2, four 3, and four 4 (and that includes room for seven future Systainers).

I am still quite the novice with SketchUp so there are many errors in the models.  And I thank Brice, jonny, and others from whom I "borrowed" models of components (the MFTs, Systainers, paper holder, basic drawer design, etc.).

I would appreciate any feedback and suggestions from this august group of more experienced woodworkers.  Thanks for looking!
Fred


Front view


Rear view

Fred, fwiw, I recently built two carts for mft3's very similar to yours.  The two mft's are joined together on the top of the carts.  I was going to include a lip/ledge like you have in your drawing to make sure the mft's stay on the top of the carts and don't slide around.  After using them for a few weeks (doing everything from crosscutting, routing, assembling, and hand planing) I've found it unnecessary to include something like that.  The rubber feet on the bottom of the mft's have kept the benches firmly in place.

Willy:  Good suggestion about the height--I hadn't even considered that and it's an easy change to make now before I have started cutting plywood.  The drawers are designed not to have any handles and the outer surface of the sliding deadman is designed to be aligned with the MFT side rails.  I didn't draw it (I stole a component someone else designed instead), but I'm thinking I'll probably use a deadman that includes a Bessey toggle clamp fitted to a slot (allowing for vertical height adjustments) instead of the pegboard.

Russell:  What rubber feet are you referring to?  I don't see any on my older MFTs (after removing the legs) and I just looked at some photos of the newer MFT3s and don't see them their either.  Were they something you added?

Michael:  Good ideas as well.  I keep going back and forth on blocking the end of the table for the paper.  Where it is currently located there is no room beyond the bench to hang something out further but I may want the flexibility for the future.  I don't have a miter station yet--another good idea to incorporate into the design.

Thanks to all of you for your input--these are exactly the sorts of suggestions I am hoping for!
Fred

I agree that I'd put the paper roll on the side and not above.

Also, I don't know what the distance between the carcase top and the MFT top is, but is it enough to get clamps in from underneath?  Just doesn't seem high enough to me, but may be.

I agree that the paper needs to move.

I'll have to look around for the rubber feet--I may have them rat-holed somewhere.  Thanks for the part number, Corwin.

Dick:  I am planning on joining all three tables together using the MFT table connectors.  If I need more stability to resist lengthwise racking (e.g., while planing) then I figured I could bolt the sidewalls together.  As for leveling, me the fudgehead hadn't thought about that issue.  I suppose I could shim under the wheels (better to do it at the bottom so the shelves are also level) or substitute leveling casters.  I'll do a search for some reasonably priced options.

Jay:  There's just enough room under the tables to fit Jorgensen hold-down clamps (image at Jorgensen Hold-Down Clamp).  I usually use the Festool clamps upside down (with the handle end sticking up into the air), so I didn't think I would need more room underneath.  Good point that I'll have to think about.

Thanks for the additional input--please keep it coming!
Fred

Instead of having the lip/ledge on the outside of the MFT feet you could consider to screw some blocks on the cabinet tops at the inside of the MFT feet, enabling to pair the MFT width-wise and length-wise. It will make your cabinets slightly smaller, so it might take some rework in sketchup.

Fred, you might want to look at this photo to see how I used 1/4" plywood blocks to keep the MFT from inadvertently sliding off the SysPort.  The top of the MFT was removed for the photo.  The feet that Russell is referring to are part of the MFT/3's base.  If the legs are folded up, the four corners will be sitting on light gray feet rather than have the aluminum corners sitting directly on the floor (or on top of the SysPort).  I'm not familiar enough with the older MFT 1080 to know if it has similar feet, but I can't imagine it not having them. 

Thanks to everyone for the additional suggestions.  I like the alternatives for blocking the MFTs in place if needed (but I'll probably try it without anything at first--I had never noticed the rubber feet on the MFTs and it sounds like they were sufficient in Russell's set-up).  Russell, thanks for posting the link to your build--somehow I completely missed that thread.  Still haven't decided about the feet, which will impact the height of the sides so that I end up with a 900 mm finished height.  If I use casters, I'm thinking of Zambus style ones that sit on big rubber pads when lowered--I have them on my bandsaw and jointer/planer and they seem really solid to resist racking.

Thanks again!
Fred

The Festool 4 1/2" clamps are just workable, but fiddly. I also use the Jorgensens when I don't want a handle sticking up.