We all need support!

 I have always attached the legs to all of my previous layouts and I see no reason to change.
Liking to keep things simple, a method of keeping the legs in place is one that I came across quite by accident a long time ago.
With the legs attached by hinges to the end of each board- one board has two- a way of keeping them in position was considered. Enter the humble screw block available from most DIY outlets at very reasonable cost- these are the things that keep flat pack furniture hopefully at right angles and therefore square.

An elongated Z shaped bar is produced with 3mm diameter rod which has each end bent to a right angle, preferably in the same plane!
These rods are them simply inserted into the blocks which keep the whole lot upright and rigid.
There- said it was simple.

Legs

Support for any layout can be many and choices vary.
I always look for the simple way and believe that the system I use is about as basic as it comes.
The legs are attached to the baseboard with hinges and fold under and secured with a turnbuckle.
A plastic block, two holes one way and one the other, from most DIY outlets are attached- one to the baseboard frame and one to the leg. These are measured for positioning by a piece of steel which has been bent at 90degrees at each end.
The two ends simply push into the holes and to date have not come adrift. Simple provided the stays arn't left at home!