Brunelleschi's turnips

Today we use rapid prototypes
made from computer files to show
the shapes in 3-D, stop the gripes
of those who need to know

Just exactly what the thing alone
is, to hold it in your hands
before it’s carved from hard stone
a prototype quickly disbands

Mistaken notions, it’s clear to see
what a designer intended
and makes it easy to be
sure of the work, doubt’s suspended.

But back in Brunelleschi’s day
no rapid prototype craftsmanship
he used his own unique way:
he carved shapes from a turnip.

Carved turnips showed the masons
the shapes he wanted for his work
otherwise he would be facin’
long delays and unclear murk.