@texgeekboy,
I have similar plans, although they'll probably end up in an around-the-room format, rather than in a rectangle, but I think that the process, and construction details would be similar.
Follow this forum link as a start:
Benchwork for Portable Layout | CARGUYZM19
As Dave and John mentioned above Mianne benchwork is an excellent example of a prefabricated solution, however I don't think that it can be assembled on your driveway, or in your garage, then carried upstairs to its final destination.
I'm thinking "foldable legs", but I haven't been able to find anything prebuilt with foldable or removable legs, except for common folding tables. There are however clubs with members on this forum that use them extensively for traveling layouts. You might try entering "folding tables" in the 'Exact Phrase Match' search box on the forum search page and see what comes up.
There was a two-piece modular table-style layout with removable legs that was up on eBay at one time by seller modelrailscenes. This seller apparently makes layouts like the one your searching for, but they're very expensive.
Here's a good around-the-room modular layout plan by fellow forumite and master layout artist @Ken-Oscale:
8X14 Layout idea from 2X6 modules | Ken-Oscale
See: https://ogrforum.com/...70#73791479765406570
My plan is to make the modules, as simply and inexpensively as possible, but also to ensure that they're sturdy and have a measure of flexibility that common folding table do not, for horizontal and vertical features like valleys, and bump-outs.
So, pulling from the extensive history on this forum, and elsewhere, here are some building blocks:
1.) @Tom Tee'sstick-framed style structure and materials -- Stringers made out of Baltic birch plywood; relatively lightweight but strong; easily supports vertical and horizontal extensions. I'd like to build 3 to 4 foot wide modules, perhaps 5 to 6 feet long, longer if narrower, that fasten to adjacent modules at the ends. Note the pre-drilled holes for wiring. You could contact Tom about making these for you. I'm also seen Sievers or Model Railroad Benchwork examples, and others, that would support this kind of modularity. One of these sources could probably custom-make them for you.
See: https://ogrforum.com/...7#143467552946965637
2.) Foldable and/or removable legs -- Must be foldable or at least easily installed and removed. There are foldable mechanisms and leg assemblies (like those under common rectangular folding tables) available online, for example on eBay and from Amazon. One example of brackets for removable legs is Leg-o-matic from BMI Supply Co. For hardware to make folding legs, try seller moinhardwareinc on eBay.
Leg-o-matic (BMI Supply, Inc.)
Folding Leg Bracket (moinwardwareinc)
3.) Module Standardization -- If you have interested in taking some of one or more of your modules to join up with a club's portable layout at some point, for instance at shows or holiday events, it would be wise to make sure that yours can couple, mechanically and electrically, with theirs. There are several existing standards for doing so, including those from Lionel itself, and modular groups like North Penn O-Gaugers, Independent HiRailers, and National Capital Trackers. Here's a link to the Lionel Fastrack Modular Railroad Specification, and one for a kit for building a straight section (you must provide the plywood for the top):
Lionel FasTrack Modular Railroad Specification Manual, Ver 2.0 | Lionel
Fastrack Modular Railroad Straight Section Kit | Lionel
FasTrack Modular Railroad Straight Section Kit (Lionel)
4.) Joining together -- You can use plain old bolts and nuts to hold the sections aligned and securely held together, or something fancier, like Coffin Locks, which are featured in the FasTrack Modular Specification, which uses two sets of this kit, to join adjacent modules:
Coffin Locks (Musson Theatrical)
A clever method for alignment, that was mentioned in a previous thread on this forum, I believe by Tom in fact, uses Square Head Brass Dowels, with a male square head threaded into a hole on one module and the same-sized female hole threaded into a hole on the adjacent module:
Square Head Brass Dowels (Freeman Manufacturing & Supply Co.)
Whichever way you approach this good luck with it. You're going to be busy whether you make or buy.
I'm a ways off from starting mine. Just gathering information now.
Mike