I have an area that needed something - either a bridge or a trestle. But, it seemed too low for a trestle - or any kind of above track bridge.

While thinking of what to do, I came up with the idea to create a stone bridge.
I figured I wanted something low, with arches.

I had a bunch of pink Styrofoam left over from doing my track that I thought might work.

So, first things first.

It's about 40 inches long and about 5 inches high. Perhaps a bit less, but I figured better to dig than fill.

So, cut some strips and glued them together.

I cut some arches and it began to take shape.
 

Next, was to put in some stone. I tried scribing with different objects but nothing really worked. I tried using styrene glue, but felt I really didn't have enough control!
Finally, I tried the soldering iron and a straight edge, and I think that worked!

Here it is with an undercoating of aged concrete.