Just individual sections of charts. Our airport has IFR sectionals to
make up such a map. They just trim the white parts off, then start
pasting. You'll notice that not everything matches up, due to trying to
map the curve of the earth on a flat sheet of paper.

I'm trying to do something similiar with VFR sectionals on one my living
room walls, more or less centered on the area I fly. Covers a good
section of the upper midwest.

Note that if the wall map you see really is of VFR sectionals, your FBO
must have some really tall walls. Mine starts with the northern Green
Bay sectional and ends with the southern chicago sectional, about 4
charts high. I have room for most of the northern parts of the Kansas,
St Louis, and Cincinnati sectionals at the bottom (anyone have any
unmarked expired sectionals of these they can part with?).
From the eastern end, I have the detriot and lake huron sectionals, and
the westernmost end has the twin cities northern chart, and below that
is a doorway, with parts of the TC and omaha charts going up to the
doorway.

I can only imagine what a full US map made of VFR sections would look
like, just HUGE!

John