OK something useful at last, well I hope so.
The concept of the under-frame/baseboard as set out in the 2mm Association's Beginner's Guide is to construct it from materials “as found, being left over from various household DIY tasks”. This seemed like a good idea to me so I rummaged around in my shed, you do have a shed full of bits and pieces don't you? No, then its the DIY store I'm afraid.
Well my shed yielded some aluminium channel, 15mm by 15mm and some 12mm MDF which slotted nicely into the channel. Result! Having decided on the size of the layout I cut the channel to suite and fitted three MDF stretchers. I had to buy four rubber feet so as not to damage the table and the under-frame was finished. Cost £1.50 so far.
Onto the under-frame is fitted a baseboard which is conventional in being softwood sides and ends and a plywood top. The only softwood I could find in my shed was a rather massive 45mm by 20mm, still I was not about to start buying materials so I used that to build a rectangular frame topped by 9mm plywood, also from the stock pile.
At one end I cut out a section of the plywood top to accommodate a train table. Hopefully you will see what I mean from the photograph.
Good job I throw nothing away! The Beginner's Guide suggests 35mm by 9mm softwood for the frame and 6mm plywood for the top. Clearly lighter if this is what you have already or are going to buy. I don't think Marks Quay as going to warp!
To be honest either way is not expensive but I wanted to do it as cheaply as possible, why, because I could. Cost so far, still £1.50.
Well that concludes the under-frame/baseboard, the next instalment will be to decide on the track plan and track construction.