Staying on topic !

Mick Benton said:

 

Mik,

  Try to stay on topic as suggested by the experts?

Mick Benton said:

 

THAT and Rooster's video with stone aqueduct bring to mind a long-ago story in some model railroad magazine where the modeler had the Einsteinian Inspiration to make their stone viaduct out of poured concrete or plaster, I forget which, and it turned out that drink cans were just about perfectly sized for the arches.

So ...

a form was made ...

with stacked drink cans under something thin and flexible ...

it worked like a charm.

Until ...

until the setting poured material did something exothermic ...

and that interacted with the drink cans ...

which no one had thought to empty beforehand ...