I'll get a shot of the underside when I haul it back up. It's quite simple, just two side rails and three cross pieces with the sheets screwed on. I was going to use single piece side rails but couldn't get the four metre long bits of wood home in the car. So they're made up of a pair of two metre lengths bolted to another two metre length.
It's a bit flimsy but I wanted to keep the weight to a minimum. It doesn't matter if it warps or sags a bit, I won't be using it for anything other than as a base for set track layouts.
And, yup, at the moment, I'm using $20 workbenches from Bunnings. Later on, I plan to make some folding legs with castor wheels so I can move it about. PhilR uses folding saw horses bolted to his portable track pieces and I think I'll do something like that if I can work out how to attach the castors.
Here's a shot of one of the winches. They're attached to the rafters and require a small step ladder to operate.
There are four lengths of chain, one at each corner, to secure the table to the rafters when it's up and to help lower it all down. The chains at one end are long enough to hook up when the table is down. To lower the table, I wind the winch at the long chain end up enough to unhook it from the storage position (leaving the other end attached to the chains) then lower it enough to allow the table to swing freely, then reattach the chains and release the cable tension a bit. Then I lift the other end slightly to unhook the chains and lower that end straight onto the support, leaving a bit of tension on the cable. Then it's just a matter of lowering the other end onto the support. I leave the cables connected with a bit of tension for added security, they don't get in the way.
It's a slightly complicated process to get it up and down but it's fairly quick and keeps the mechanism simple. I'll post some pics when I've finished playing
It's a bit over complicated but, for aesthetic reasons, I wanted to hide everything as much as possible.