No, I’m not referring to paint finish. Flat should mean flat in any case there. Of course it is also mixed in with matt, matte, eggshell, lustre, and a number of other descriptive words. When in doubt, paint a sample.
I really mean the basic necessity for all scratch or kit builders…a flat surface. Some portion of the big world upon which to erect some portion of the little one. It is closely aligned to the other necessity – a right angle. These sound easy enough to do but practice shows how hard it is to get them.
Model airplane builders need a flat base to act as a measurement basis for the curves of the fuselage and the angle of the wings. They need a flat base for the undercarriage, and a level flat base to set up the aircraft. The vertical stations that might be measured on a plan need to rise from this base at 90 degrees.
The model ship builder needs that level ground to also establish rib positions. Unlike the full-size counterpart, there’s no need to use gravity to slide the model into the water. so you don’t need to build on a slope.
The model architect absolutely needs a level flat base to raise walls and structures. Even if there isn’t a straight line in the building, the thing has to be vertical. Pisa was a mistake…and Gaudi a greater one…
My solution for my workshop has been to use a commercial whiteboard in a frame laid on top of a standard trestle table. It is a smooth Laminex surface bigger than any of the model foundations I use, supported with a 25mm-thick MDF board captured in a metal frame. Glue does not stick to it and when it is truly horizontal everything erected upon it is true as well.
Currently I use a small modeller’s set square for much of the setups, but will purchase a larger metal square in the future. You cannot have enough precision.
Note: the whiteboard is far larger than most building models but the extra room can be used to set up clamps and jigs to hold building components as they set. As long as I do not need to nail to it, I can build anything.